Isolation and characterization of hydroxyproline-containing proteins secreted by a murine carcinoma cell culture

A collagenous protein was isolated from a murine carcinoma cell culture, which has been shown to synthesize basement membrane. The molecular weight of this protein was estimated to be 155 000. It eluted from carboxymethyl-cellulose in the region near the alpha 1 and beta 11 components of calf skin collagen. 63--69% of the peptide-bound prolines were hydroxylated, and the 4-/3-hydroxyproline ratios ranged from 12 : 1 to 14 : 1. About 95% of the hydroxylysines in the peptide were glycosylated, and almost all of them were in the glucosylgalactosyl dissacharide form. Judging from the posttranslational characteristics, this collagenous protein is probably of basement membrane type.