Antibodies to a precursor of human collagen.

Antiserum prepared against serum-free medium from human fibroblast cultures reacted specifically with protropocollagen, an assembled, soluble precursor of tropocollagen. The antibodies were directed to antigenic determinants in the nonhelical, amino terminal peptide extensions (propeptides). Amino acid sequences in the precursor molecule corresponding to the telopeptides and helical alpha chains of tropocollagen were not recognized by the antiserum.