阅读说明：本技术 高亲和pvr突变体 (High affinity PVR mutants ) 是由 赵文珊 高艳锋 周晓文 周秀曼 祁元明 吴亚红 翟文杰 于 2020-12-24 设计创作，主要内容包括：本发明公开了几种高亲和PVR突变体,通过将野生型PVR或其同工变体的某氨基酸位点突变得到与TIGIT具有更高亲和力的PVR突变体。本发明的PVR突变体,亲和力高。本发明还提供了该突变体或其制剂在制备治疗、预防、或者缓解肿瘤相关疾病等药物中的用途。(The invention discloses several high-affinity PVR mutants, and PVR mutants with higher affinity with TIGIT are obtained by mutating certain amino acid positions of wild-type PVR or isovariant thereof. The PVR mutant of the invention has high affinity. The invention also provides the application of the mutant or the preparation thereof in preparing medicaments for treating, preventing or relieving tumor-related diseases and the like.)

A PVR protein mutant having an amino acid sequence with at least one of the following characteristics compared to a human wild-type PVR protein or an isovariant thereof:

A. the 72 th amino acid is R or W

B. The 131 th amino acid is V

C. Amino acid 132 is Q or N.

2. The PVR protein mutant according to claim 1, wherein the mutant has an increased affinity for the eukaryotic protein hTIGIT-Fc compared to the human wild-type PVR protein.

3. The PVR protein mutant according to claim 1 or 2, wherein the wild-type PVR protein or the isovariant thereof comprises an amino acid sequence as shown in SEQ ID No. 1, and wherein the wild-type PVR protein sequence is SEQ ID No. 1.

4. A PVR protein mutant according to any preceding claim which is a human protein.

5. The PVR protein mutant according to claim 1, wherein the mutant is selected from one of four single amino acid position mutants of wild-type PVR shown in SEQ ID No. 1: S72R, S72W, G131V or S132Q.

6. A nucleic acid molecule encoding a PVR protein mutant according to any preceding claim.

7. A vector comprising the nucleic acid molecule of claim 6.

8. A cell comprising the nucleic acid molecule of claim 6 or the vector of claim 7.

9. A pharmaceutical composition comprising a PVR protein mutant according to any preceding claim, a nucleic acid molecule according to claim 6, a vector according to claim 7 and/or a cell according to claim 8, and optionally a pharmaceutically acceptable adjuvant.

10. Use of the PVR protein mutant of any preceding claim, the nucleic acid molecule of claim 6, the vector of claim 7, the cell of claim 8 and/or the pharmaceutical composition of claim 9 in the preparation of a medicament for treating, preventing and/or ameliorating a TIGIT-associated disease.

The technical field is as follows:

the invention relates to the field of molecular biology, in particular to a high-affinity PVR protein mutant, a protein structure, corresponding amino acids, a corresponding gene sequence, a preparation method and application.

Technical background:

in recent years, malignant tumors are one of the most serious diseases that endanger human health. Tumor immunotherapy has become the most attractive treatment method following traditional surgery, radiotherapy, chemotherapy, targeted therapy. The immunotherapy of immunosuppression targeting tumor microenvironment is the first of ten scientific breakthroughs reviewed in the journal of science in 2013. Nobel's physiology or medicine was awarded in 2018 to two immunologists in the field of tumor immunotherapy to show their contribution in the field of cancer immunity.

The immune response process is a delicate balance process of various immune cell inflammation-causing mechanisms and anti-inflammatory mechanisms in the body, and the balance process depends on the interaction of ligands on immune cells and the participation of a cytokine network. In the course of tumor immunotherapy, T cells are the core performers of the tumor immune response. Regulatory receptors on the surface of T cells include positive and negative costimulatory molecules that precisely regulate T cell function. Wherein the negative co-stimulatory molecule is an immune checkpoint molecule. Immune checkpoint molecules on the surface of T cells interact with over-expressed ligands on tumor cells, causing T cells to be trapped in a depleted state, resulting in tumor immune tolerance and immune escape and poor tumor treatment. Currently, immune checkpoint molecules known to be expressed on T cells include: CTLA-4, PD-1, TIM-3, LAG-3, TIGIT, etc.

TIGIT molecule is a newly discovered T cell regulatory receptor with immunosuppressive effect in recent years, belongs to PVR/nectin protein family, and ligand molecules of TIGIT comprise: CD 155. CD155, also known as PVR or nectin-like 5, is mainly expressed in Dendritic Cells (DCs) and various tumor cells and the like.

The study of the TIGIT/PVR pathway and the development of inhibitors have potential in the field of cancer immunotherapy. Therefore, the PVR high-affinity mutant designed as a competitive inhibitor of a TIGIT/PVR signal channel has important application value in breaking tumor immune tolerance.

Disclosure of Invention

In one aspect, the invention provides several high affinity PVR protein mutants having an amino acid sequence that is at least one of the following features compared to a wild-type human hPVR (the h abbreviations are all herein denoted human) protein or an isovariant thereof:

A. the 72 th amino acid is R or W

B. The 131 th amino acid is V

C. Amino acid 132 is Q or N.

The isovariant is a PVR protein that retains binding to TIGIT, may be from a different species, may be a truncated protein of a wild species or a protein derivative fused to other sequences.

Alternatively, the above PVR protein mutant has a higher affinity for the eukaryotic protein hTIGIT-Fc than the human wild-type PVR protein.

Optionally, the wild-type PVR protein or an isogenic variant thereof comprises an amino acid sequence as shown in SEQ ID No. 1, and the sequence of the wild-type PVR protein is SEQ ID No. 1.

Optionally, the mutant is a human protein, such as one of four single amino acid site mutants selected from wild-type PVR shown in SEQ ID NO: 1: S72R (protein with the 72 th amino acid changed from S to R, which is also referred to herein as the abbreviation method for other mutants), S72W, G131V or S132Q.

Further, the invention provides an isolated nucleic acid molecule encoding any of the previously described PVR protein mutants.

Further, the present invention provides a vector containing the above-mentioned nucleic acid molecule.

Further, the present invention provides a cell containing the above nucleic acid molecule or vector.

In the present application, the term "isolated nucleic acid molecule" or simply "nucleic acid molecule" generally refers to a DNA or RNA of genomic, mRNA, cDNA, or synthetic origin, or some combination thereof, that is not associated with all or a portion of a polynucleotide found in nature, or is linked to a polynucleotide to which it is not linked in nature.

In the present application, the term "vector" generally refers to a nucleic acid molecule capable of self-replication in a suitable host, which transfers the inserted nucleic acid molecule into and/or between host cells. The vector may include a vector mainly for inserting a DNA or RNA into a cell, a vector mainly for replicating a DNA or RNA, and a vector mainly for expression of transcription and/or translation of a DNA or RNA. The vector also includes vectors having a plurality of the above-described functions. The vector may be a polynucleotide capable of being transcribed and translated into a polypeptide when introduced into a suitable host cell. Typically, the vector will produce the desired expression product by culturing a suitable host cell containing the vector.

In the present application, the term "cell" generally refers to an individual cell, cell line or cell culture that may or may already contain a plasmid or vector comprising a nucleic acid molecule described herein, or that is capable of expressing an antibody or antigen-binding fragment thereof described herein. The cell may comprise progeny of a single host cell. Due to natural, accidental, or deliberate mutation, the progeny cells may not necessarily be identical in morphology or in genome to the original parent cell, but may be capable of expressing an antibody or antigen-binding fragment thereof as described herein. The cells can be obtained by in vitro transfection of cells using the vectors described herein. The cell may be a prokaryotic cell (e.g., E.coli) or a eukaryotic cell (e.g., a yeast cell, such as a COS cell, a Chinese Hamster Ovary (CHO) cell, a HeLa cell, a HEK-293 cell, a COS-1 cell, an NS0 cell, or a myeloma cell). In some cases, the cell may be a mammalian cell. For example, the mammalian cell may be a CHO-K1 cell. The more specific term "recombinant cell" is sometimes used in the art to generally refer to a cell into which a recombinant expression vector has been introduced. The recombinant host cell includes not only a specific cell but also a progeny of such a cell.

Further, the present invention provides various pharmaceutical forms comprising the above PVR protein mutants, which may occur in various forms in a medicament, such as proteins, nucleic acid molecules, vectors, cells; such as a preparation, containing the PVR protein mutant. In the present application, the term "pharmaceutically acceptable adjuvant" generally includes pharmaceutically acceptable carriers, excipients, or stabilizers which are non-toxic to the cells or mammals exposed thereto at the dosages and concentrations employed. Typically, the physiologically acceptable carrier is an aqueous PH buffered solution. Examples of physiologically acceptable carriers may include buffers such as phosphate, citrate and other organic acids; antioxidants, including ascorbic acid; low molecular weight (less than about 10 residues) polypeptides, proteins, such as serum albumin, gelatin or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents, such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions, such as sodium; and/or nonionic surfactants such as TWEENTM, polyethylene glycol (PEG) and PLURONICSTM.

Accordingly, the invention discloses medical application of the PVR protein mutant or various medicinal forms thereof, such as: the application of the compound in preparing medicines for treating, preventing or relieving TIGIT related diseases and the like. The TIGIT-associated disease may be a T cell dysfunctional disorder. T cell dysfunction is manifested in T cell depletion, and the treatment or delay or alleviation of diseases is realized by enhancing NK cells, activating T cells and enhancing the immune activity of organisms. For example, the TIGIT-associated disease may be a tumor, a cancer, or an infectious condition. For example, the TIGIT-associated disease may be a PVR-positive or PVR-positive tumor, cancer, immune disease, or infectious disorder, including a tumor, cancer, immune disease, or infectious disorder, among others. TIGIT-associated diseases may specifically be selected from the group consisting of: breast cancer, colon cancer, liver cancer, lymphoma, chondrosarcoma, multiple myeloma, lung cancer, kidney cancer, melanoma, T lymphoma, pancreatic cancer.

The invention has the advantages that: the high-affinity PVR protein mutant provided by the invention is obtained by mutating the amino acid sites of wild-type PVR or isovariant thereof, so that the PVR protein mutant with higher affinity can be obviously reduced and T cell activation and cytokine secretion can be obviously reduced, and meanwhile, the dosage can be reduced and the treatment cost can be reduced.

Description of the drawings:

FIG. 1 is a diagram representing the localization of plasmid pLVXpuro-hPVR and its mutant on CHO-K1 cell membrane in the example, wherein the left gray peak of each sample graph (e.g. PVR) in flow detection results is an isotype control, and the right side shows the expression of target protein on CHO-K1 cell membrane constructed to stably express PVR target protein.

FIG. 2: in the examples, the binding of hPGR (hPGR) (WT) and its mutants to hTIGIT-Fc protein was examined by flow cytometry.

FIG. 3: examples hPGR and its mutants have effects on IL-2 secretion by TIGIT.

Detailed Description

Hereinafter, F represents the forward primer, and R represents the reverse primer.

Example 1: construction of lentiviral vector pLVXpuro-hPVR.

(1) And (3) PCR amplification: the hPVR gene was amplified from cDNA using KOD-Plus-Neo high fidelity amplification enzyme (TOYOBO).

The amplification primers are as follows:

hPVR-F:aaggatccgccaccatggcccgagc；

hPVR-R:cctctagatcaattacggcagctct；

the PCR conditions were: 94 ℃ for 2min, 98 ℃ for 10s, 55 ℃ for 2min, after 25 cycles, 68 ℃ for 5 min.

(2) And (3) recovering PCR product gel: the PCR product was subjected to DNA gel electrophoresis, and then purified and recovered according to the instructions of a DNA gel recovery kit (AXYGEN) to obtain an hPVR gene fragment.

(3) Enzyme digestion of target gene and vector: the target fragment recovered from the gel in step (2) and the lentiviral vector pLVX-puro (self-preserved in the laboratory) were digested with the endonucleases BamHI, XbaI (NEB) at 37 ℃ for 2 hours.

(3) And (3) recovering the enzyme digestion product gel: and (3) carrying out DNA gel electrophoresis on the enzyme digestion product, and purifying and recovering according to the instruction of a DNA gel recovery kit (AXYGEN) to obtain the hPVR gene fragment.

(4) And (3) connecting and transforming the target fragment with a vector: the target fragment and the vector pLVXpuro are connected by T4 DNA ligase, the obtained target plasmid pLVXpuro-hPVR is transformed into XL-1Blue competence, and the transformed product is coated on an LB Amp plate.

(5) Sequencing and identifying: and (4) picking a monoclonal from the plate in the step (4), shaking bacteria, and sending to a gene company for sequencing. Sequencing results show that the lentiviral vector pLVXpuro-hPVR is successfully constructed.

Example 2: construction of pLVXpuro-hPVR mutein lentiviral vector

(1) Designing a PCR primer: primers for the four hPVR protein mutants are designed according to the gene sequences and codon tables of the hPVR mutant proteins. The gene sequence of the mutant protein follows:

mutant S72R:

mutant S72W:

mutant G131V:

mutant S132Q:

the primer sequence is as follows:

mutant S72R

hPVR-S72R-F:gcggcatggtgaacgtggcagcatggccgt；

hPVR-S72R-R:acggccatgctgccacgttcaccatgccgc；

Mutant S72W

hPVR-S72W-F:gcggcatggtgaatggggcagcatggccgt；

hPVR-S72W-R:acggccatgctgccccattcaccatgccgc；

Mutant G131V

hPVR-G131V-F:cacgttcccgcaggtcagcaggagcgtgga；

hPVR-G131V-R:tccacgctcctgctgacctgcgggaacgtg；

Mutant S132Q

hPVR-S132Q-F:gttcccgcagggccagaggagcgtggatat；

hPVR-S132Q-R:atatccacgctcctctggccctgcgggaac；

(2) And (3) PCR amplification:

the reaction system for PCR amplification of the hPVR mutant protein gene is as follows: 50nghPVR DNA template: 1 mu L of the solution; 10 μ M forward primer: 1 mu L of the solution; 10 μ M reverse primer: 1 mu L of the solution; 10 × Buffer: 5 mu L of the solution; 2mM dNTP: 5 mu L of the solution; 25mM MgSO₄：3μL；KOD-Plus-Neo(1U/μL)：1μL；ddH₂O: 43 μ L, 50 μ L total.

The PCR reaction conditions are as follows: 94 ℃ for 2min, 98 ℃ for 10s, 55 ℃ for 30s, 68 ℃ for 8min, 15 cycles later, 68 ℃ for 10 min.

(3) DNA gel electrophoresis and purification of PCR products: a1% agarose gel was prepared, and 5. mu.L of the PCR product was added to 1. mu.L of 6 XLoadingBuffer, spotted, and subjected to 200V electrophoresis for 15 min. After the band of interest was detected by electrophoresis, the remaining 45. mu.L of PCR product was subjected to DNA fragment purification.

(4) DpnI digestion: the pLVXpuro-hPVR template was cleaved with Dpn I (NEB). Enzyme digestion system: 44 μ L of the purified DNA product; 10 × CutSmartbuffer 5 μ L; DpnI: 1 μ L. The enzyme digestion reaction conditions are as follows: at 37 ℃ for 2 h; 80 ℃ for 40 min.

(5) Transformation and sequencing identification: transferring the Dpn I enzyme digestion product into XL-1Blue competence, and coating the converted product on an LB Amp plate. The next day, single clones were picked, shaken and sent to Huada Gene for sequencing.

Sequencing results show that the lentiviral vectors containing the hPV gene mutants are successfully constructed and are respectively named as pLVXpuro-hPV (S72R), pLVXpuro-hPV VR (S72W), pLVXpuro-hPV (G131V) and pLVXpuro-hPV (S132Q).

Example 3: construction of hPVR and hPVR gene mutant overexpression stable cell line

3.1 cell recovery and culture

(1) Resuscitating HEK-293T cells and CHO-K1 cells: fresh DMEM, RPMI 1640 medium was pre-warmed in a 37 deg.C water bath. HEK-293T cells and CHO-K1 cells were removed from a-80 ℃ freezer, quickly placed in a 37 ℃ water bath and thawed by slow shaking. The thawed cell suspension was centrifuged at 25 ℃ for 5min at 1000 rpm. After centrifugation, the supernatant was aspirated, HEK-293T cells were added to 1mL of pre-warmed DMEM medium, and CHO-K1 cells were resuspended in 1mL of pre-warmed RPMI 1640 medium. Transferring the cell suspension to a culture dish, adding the corresponding culture medium to 10mL, gently shaking uniformly, placing at 37 ℃ and 5% CO₂Culturing in an incubator.

(2) Cell passage: when the cells were spread to the bottom of the dish, the old medium was aspirated away. After the cells were rinsed by slowly adding 10mL of PBS7.2 using a pipette gun, PBS7.2 was aspirated off. 1mL of 0.25% pancreatin was added, and cells were observed under a microscope to be rounded, and when the cell gap was increased, pancreatin was removed. 3mL of fresh medium was added to stop digestion, and the cells were blown off by gentle pipetting with a pipette. Dividing the cell suspension into 3 culture dishes, supplementing the culture medium to 10mL, placing at 37 ℃ and 5% CO₂Culturing in an incubator.

3.2 Lentiviral packaging

(1) HEK-293T cells are laid in a six-well plate, and transfection can be performed when the cell density is observed under a microscope on the day of transfection and the cell confluency reaches 80-90%.

(2) HEK-293T cells were discarded from the old medium and replaced with 1mL of fresh DMEM medium without diabody.

(3) Helper plasmids PMD2.G and PSP were added to the transfection reagent powertrans 293AX₂And the target plasmid pLVXpuro-hPGR/pLVXpuro-hPGR (S72R)/pLVXpuro-hPGR (S72W)/pLVXpuro-hPGR (G131V)/pLVXpuro-hPGR (S132Q) are mixed evenly to form a liposome-DNA complex. The liposome-DNA complex was added to HEK-293T cells.

(4) Fresh DMEM medium was replaced at 6h, and at 48h of transfection, virus was harvested and cell debris removed by filtration through a 0.45 μm filter.

3.3 Virus infection of CHOK1 cells

(1) The virus solution was added to a 6-well plate containing CHOK1 cells with a confluency of 30-40%, and Polybrene was added thereto at a concentration of 1. mu.g/mL. The 6-well plate was sealed with a sealing film and infected by centrifugation (2000rpm, 30min, 25 ℃).

(2) At 4h of infection, 500. mu.L of medium was supplemented. After 24h of infection, the virus-containing medium was aspirated, replaced with fresh complete medium, and the culture was continued at 37 ℃.

Example 4: hPVR and hPVR mutant cell membrane location detection

(1) After 48h of transfection, the old medium was discarded. After being rinsed with 10mL of PBS7.2, the cells were digested with 0.25% pancreatin until they became round under the microscope and the cell gaps became large. Adding fresh RPMI 1640 culture medium, and re-suspending to obtain single cell suspension.

(2) The cells were arranged in a 3X 10 order⁵The tube/tube is subpackaged in a 1.5mL centrifuge tube; the medium was discarded by centrifugation (2000rpm, 5min, 4 ℃). Wash once with PBS7.2, centrifuge (2000rpm, 5min, 4 ℃) and discard PBS.

(3) Anti-human hPGR (eBioscience) or its isotype antibody was added to the cells and incubated on ice for 30 min. Rinsing with 1mL PBS7.2 once, centrifuging (2000rpm, 5min, 4 ℃) to remove PBS, adding 200 μ L Buffer to resuspend into single cell suspension, and detecting the expression of hPVR and hPVR mutant protein on the membrane by flow machine.

Example 5: mutant affinity detection FACS

(1) The purchased Human-hTIGIT-Fc protein (Nano Biological Inc.) was completely dissolved in 250 ng/. mu.L of a protein solution using sterile water, and the protein solution was dispensed into low-adsorption centrifuge tubes and stored in a-80 ℃ refrigerator.

(2) CHO-K1 cells overexpressing hPGR, hPGR (S72R), hPGR (S72W), hPGR (G131V) and hPGR (S132Q) were incubated with eukaryotic proteins Human-hTIGIT-Fc at 120nM, 60nM, 30nM, 15nM, 7.5nM, 3.75 nmM and 1.875nM, respectively, for 30min on ice,

(3) after incubation with protein, PBS was rinsed once at 7.2, centrifuged (2000rpm, 5min, 4 ℃) and then anti-humanIgG Fc (Biolegged) antibody was added and incubated on ice for 30 min. The negative control group was not incubated with the eukaryotic protein Human-hTIGIT-Fc, only anti-Human Fc antibody was added.

(4) After incubation with antibody was complete, a rinse was performed once with 1ml of pbs 7.2. Adding 200 mu LFACS buffer to resuspend the mixture to prepare single cell suspension, and detecting the change condition of fluorescence intensity by a flow cytometer.

Example 6 of implementation: detection of influence of mutant on cytokine secretion

(1) In a 24-well plate, CHO-K1-hPVR, CHO-K1-hPVR (S72R), CHO-K1-hPVR (S72W), CHO-K1-hPVR (G131V) and CHO-K1-hPVR (S132Q) were set at 1X 10⁵Cells/well were plated.

(2) When the plates are paved for 12 hours, 2 multiplied by 10 is added into the pore plates⁵Jurkat-hTIGIT cells were co-cultured for 48h after adding 1. mu.g/mL anti-human CD3(BioGems), 0.5. mu.g/mL anti-human CD28 (BioGems). Only Jurkat-hTIGIT cells and anti-human CD3 and anti-human CD28 were added to the control group.

(3) 4h before the end of the co-culture, a blocking agent was added.

(4) During 48h of co-culture, the cells were collected into a 1.5mL centrifuge tube and centrifuged to discard the medium in the supernatant.

(5) The centrifuged cells were vortexed and mixed, 200. mu.L of 1 XFixation buffer (Thermo Fisher) was added to resuspend the cells, and the cells were fixed at room temperature for 30 min.

(6) After fixation was complete, 1mL of 1 XPermab ligation buffer (Thermo Fisher) was added and washed twice.

(7) anti-human-IL-2APC (Biolegged) antibody or isotype antibody (Rat IgG2a-APC, Biolegged) was added and incubated on ice protected from light for 30 min.

(8) After the antibody incubation is finished, washing the cells for 1 time by PBS7.2, resuspending the cells by 200uLFACS Buffer, and detecting the change of the fluorescence intensity by a flow-type computer.

The above embodiments are only used for understanding the essence of the present invention by those skilled in the art, and do not limit the scope of the present invention. Any person skilled in the art can change or modify the technical solution and the inventive concept of the present invention within the technical scope of the present disclosure.

Sequence listing

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Leu Val Leu Ser Trp Pro Pro Pro Gly Thr Gly Asp Val Val Val Gln

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Ala Pro Thr Gln Val Pro Gly Phe Leu Gly Asp Ser Val Thr Leu Pro

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Cys Tyr Leu Gln Val Pro Asn Met Glu Val Thr His Val Ser Gln Leu

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Thr Trp Ala Arg His Gly Glu Ser Gly Ser Met Ala Val Phe His Gln

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Thr Gln Gly Pro Ser Tyr Ser Glu Ser Lys Arg Leu Glu Phe Val Ala

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Ala Arg Leu Gly Ala Glu Leu Arg Asn Ala Ser Leu Arg Met Phe Gly

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Leu Arg Val Glu Asp Glu Gly Asn Tyr Thr Cys Leu Phe Val Thr Phe

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Pro Gln Gly Ser Arg Ser Val Asp Ile Trp Leu Arg Val Leu Ala Lys

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Pro Gln Asn Thr Ala Glu Val Gln Lys Val Gln Leu Thr Gly Glu Pro

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Val Pro Met Ala Arg Cys Val Ser Thr Gly Gly Arg Pro Pro Ala Gln

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Ile Thr Trp His Ser Asp Leu Gly Gly Met Pro Asn Thr Ser Gln Val

180 185 190

Pro Gly Phe Leu Ser Gly Thr Val Thr Val Thr Ser Leu Trp Ile Leu

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Val Pro Ser Ser Gln Val Asp Gly Lys Asn Val Thr Cys Lys Val Glu

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His Glu Ser Phe Glu Lys Pro Gln Leu Leu Thr Val Asn Leu Thr Val

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Tyr Tyr Pro Pro Glu Val Ser Ile Ser Gly Tyr Asp Asn Asn Trp Tyr

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Leu Gly Gln Asn Glu Ala Thr Leu Thr Cys Asp Ala Arg Ser Asn Pro

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Glu Pro Thr Gly Tyr Asn Trp Ser Thr Thr Met Gly Pro Leu Pro Pro

275 280 285

Phe Ala Val Ala Gln Gly Ala Gln Leu Leu Ile Arg Pro Val Asp Lys

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Pro Ile Asn Thr Thr Leu Ile Cys Asn Val Thr Asn Ala Leu Gly Ala

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Arg Gln Ala Glu Leu Thr Val Gln Val Lys Glu Gly Pro Pro Ser Glu

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His Ser Gly Met Ser Arg Asn Ala Ile Ile Phe Leu Val Leu Gly Ile

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Leu Val Phe Leu Ile Leu Leu Gly Ile Gly Ile Tyr Phe Tyr Trp Ser

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Lys Cys Ser Arg Glu Val Leu Trp His Cys His Leu Cys Pro Ser Ser

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Glu His His Gln Ser Cys Arg Asn

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