Structure of human‐basement‐membrane (type IV) collagen

Abstract

The complete amino acid sequence of the 914-residue-long pepsin fragment .alpha.1(IV)95 from the .alpha.1 chain of human placental basement membrane (type IV) collagen is presented. This sequence contains 12 interruptions of the collagenous triplet sequence Gly-Xaa-Yaa which varied in length from 1 to 11 residues. The distribution of amino acids between the Xaa and Yaa position was similar to that found in interstitial collagens but the extent of proline and lysine hydroxylation differed. Computer comparisons of the .alpha.1(IV)95 sequence with those of the interstitial collagen chains did not reveal any homology, whereas a comparison with the partial sequences of mouse tumor and bovine lens capsule .alpha.1(IV) showed .apprx. 85% identity. The unique sequence characteristics of type IV collagen are discussed in relation to its macromolecular structure and to the intersitial collagens.