Collagen of fibrocartilage: a distinctive molecular phenotype in bovine meniscus

Fibrocartilage of bovine knee meniscus was analyzed for major and minor collagen constituents. The main fraction (approximately 98%) of pepsin-solubilized collagen consisted of type I with a small proportion (less than 10%) of type III molecules. The minor fraction (1--2%) isolated by salt precipitation could be further resolved into type V collagen that consisted of alpha 1(V) and alpha 2(V) chains and a type II-like molecule with chains that had all the characteristics of the 3 alpha variant of alpha 1(II) found in hyaline cartilage. The articular surface zone of the meniscus appeared 2--3-fold enriched in these minor collagens compared with deeper tissue, though qualitatively the same distinctive collagen phenotype was evident throughout.