Characterization of 26K globular domain of a new basement membrane collagen

In continuing our earlier studies (Biochem. Biophys. Res. Comm. 130, 1-8, 1985) on a new collagenous component (Type XIII) from lens capsule basement membrane, we report here the isolation and characterization of a 26K protein from the 4.5 M guanidine-HCl extracts of lens capsules. The 26K protein was purified by molecular sieve and DEAE-cellulose chromatography. The protein has been characterized by amino acid composition, NaDodSO4-polyacrylamide gel electrophoresis and by immunochemical analyses. On rotary shadowing, the 26K protein appears as a globule. The available information suggests its location at the terminal end of the collagenous component. The presented data show clearly that the 26K protein is a distinct new protein, different from the earlier reported NC-1 domain of type IV collagen.