Kunitz domain polypeptide Zkun11

Abstract

Members of the serine protease family play a role in carefully controlled processes, such as blood coagulation, fibrinolysis, complement activation, fertilization, and hormone production. The enzymatic activity of the serine proteases is regulated in part by protease inhibitors that comprise a Kunitz domain. Zkun11 is a new member of the Kunitz domain protein family.

I claim:  
     
         1 . An isolated polypeptide, comprising an amino acid sequence that is at least 70% identical to the amino acid sequence of SEQ ID NO:2, wherein the isolated polypeptide comprises an amino acid sequence with the structure: C-X(8)-C-X(15)-C-X(7)-C-X(12)-C-X(3)-C (SEQ ID NO:5), where “X” is any amino acid residue and the values in parentheses indicate the number of such variable residues.  
     
     
         2 . The isolated polypeptide of  claim 1 , wherein the isolated polypeptide comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO:2.  
     
     
         3 . The isolated polypeptide of  claim 1 , wherein the isolated polypeptide has an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO:2.  
     
     
         4 . The isolated polypeptide of claim 1 , wherein the polypeptide is a serine protease inhibitor.  
     
     
         5 . The isolated polypeptide of  claim 1 , comprising the amino acid sequence of SEQ ID NO:2.  
     
     
         6 . The isolated polypeptide of  claim 5 , consisting of the amino acid sequence of SEQ ID NO:2.  
     
     
         7 . An isolated polypeptide, comprising a Kunitz domain amino acid sequence, wherein the Kunitz domain amino acid sequence shares a percent identity with the amino acid sequence of SEQ ID NO:2, wherein the percent identity is selected from the group consisting of 70%, 80%, 85%, and at least 90%, and wherein the isolated polypeptide comprises an amino acid sequence with the structure: C-X(8)-C-X(15)-C-X(7)-C-X(12)-C-X(3)-C (SEQ ID NO:5), where “X” is any amino acid residue and the values in parentheses indicate the number of such variable residues.  
     
     
         8 . The isolated polypeptide of  claim 7 , further comprising a second Kunitz domain amino acid sequence, wherein the first and second Kunitz domain sequences are separated by a linker that comprises at least about ten amino acid residues.  
     
     
         9 . The isolated polypeptide of  claim 8 , wherein the linker comprises about 20 or about 40 amino acid residues.  
     
     
         10 . The isolated polypeptide of  claim 8 , wherein the linker comprises about 60 or about 80 amino acid residues.  
     
     
         11 . An isolated nucleic acid molecule selected from the group consisting of: (a) a nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO:3, and (b) a nucleic acid molecule that remains hybridized following stringent wash conditions to a nucleic acid molecule consisting of a nucleotide sequence that is either the nucleotide sequence of SEQ ID NO:1, or the complement of the nucleotide sequence of SEQ ID NO:1.  
     
     
         12 . The isolated nucleic acid molecule of  claim 11 , wherein any difference between the amino acid sequence encoded by the nucleic acid molecule and the corresponding amino acid sequence of SEQ ID NO:2 is due to a conservative amino acid substitution.  
     
     
         13 . The isolated nucleic acid molecule of  claim 11 , comprising the nucleotide sequence of SEQ ID NO:1.  
     
     
         14 . A vector, comprising the isolated nucleic acid molecule of  claim 13 .  
     
     
         15 . An expression vector, comprising the isolated nucleic acid molecule of  claim 13 , a transcription promoter, and a transcription terminator, wherein the promoter is operably linked with the nucleic acid molecule, and wherein the nucleic acid molecule is operably linked with the transcription terminator.  
     
     
         16 . A recombinant host cell comprising the expression vector of  claim 15 , wherein the host cell is selected from the group consisting of bacterium, yeast cell, avian cell, fungal cell, insect cell, mammalian cell, and plant cell.  
     
     
         17 . A method of using the expression vector of  claim 15  to produce a protein that comprises the amino acid sequence of SEQ ID NO:2, comprising culturing recombinant host cells that comprise the expression vector and that produce the protein.  
     
     
         18 . An antibody or antibody fragment that specifically binds with the polypeptide of  claim 6 .  
     
     
         19 . The antibody of  claim 18 , wherein the antibody is selected from the group consisting of: (a) polyclonal antibody, (b) murine monoclonal antibody, (c) humanized antibody derived from (b), and (d) human monoclonal antibody.  
     
     
         20 . An anti-idiotype antibody that specifically binds with the antibody, or anti-idiotype antibody, of  claim 18.