The cell line, RCS-LTC (derived from the Swarm rat chondrosarcoma), deposits a copious extracellular matrix in which the collagen component is primarily a polymer of partially processed type II N-procollagen molecules. Transmission electron microscopy of the matrix shows no obvious fibrils, only a mass of thin unbanded filaments. We have used this cell system to show that the type II N-pro-collagen polymer nevertheless is stabilized by pyridinoline cross-links at molecular sites (mediated by N- and C-telo-peptide domains) found in collagen II fibrils processed nor-mally
