Compositions of active Wnt protein

Abstract

Compositions of purified biologically active Wnt proteins are provided. Wnt proteins are found to be hydrophobic and post-translationally modified by addition of a lipid moiety at a conserved cysteine residue. Methods for isolation of Wnt utilize detergents that maintain the solubility of the modified protein.

1 .- 5 . (canceled)  
     
     
         6 . A method of enhancing stem cell self-renewal and/or proliferation the method comprising: 
 contacting the stem cells with an effective dose of biologically active, substantially homogeneous Wnt protein comprising a lipid moiety:    wherein the stem cell self-renewal and/or proliferation is enhanced.    
     
     
         7 .- 12 . (canceled)  
     
     
         13 . The method of  claim 6 , wherein the Wnt protein is provided at a concentration of at least about 10 μg/ml.  
     
     
         14 . The method of  claim 6 , wherein the Wnt protein is a mammalian protein.  
     
     
         15 . The method of  claim 6 , wherein the Wnt protein is a human protein.  
     
     
         16 . The method of  claim 6 , wherein the Wnt-protein is purified by the method comprising: 
 expressing the Wnt protein comprising a lipid moiety in a cell;    recovering the Wnt protein from a lysate of the cell or from culture medium in which said cell is grown;    isolating the Wnt protein from said lysate or culture medium by affinity chromatography in the presence of a detergent sufficient to maintain solubility of the Wnt protein;    wherein biological activity of the Wnt protein comprising a lipid moiety is maintained in the substantially homogeneous composition.    
     
     
         17 . The method of  claim 16 , wherein the specific activity of Wnt protein in the substantially homogeneous composition is at least 5% the specific activity of Wnt protein in the lysate or culture medium.  
     
     
         18 . The method of  claim 6 , wherein the Wnt protein is selected from the group consisting of human Wnt 1, Wnt 2, Wnt 2B, Wnt 3, Wnt3A, Wnt 4, Wnt 5A, Wnt 5B, Wnt 6, Wnt 7A, Wnt 7B, Wnt 8A, Wnt 8B, Wnt 10A, Wnt 10B, Wnt 11, Wnt 14, Wnt 15, Wnt-16a, and Wnt-16b.  
     
     
         19 . The method of  claim 6 , wherein the Wnt protein is Wnt3A.