Biochemical properties and immunolocalization of minor collagens in foetal calf cartilage.

Type II collagen is the major collagen of cartilage. However, new collagenous chains have been described in different cartilaginous tissues, recently. The la, 2a and 3a chains were extracted from human and bovine hyaline cartilage [1]. Other minor collagenous components were extracted from neonatal pig and human cartilage noted M, CFI, CF2 [2-4], from bovine nasal cartilage and human intervertebral disc noted CPS1, CPS2 [5,6] and from chicken sternal cartilage noted HMW, LMW [7,8] and M 1, M 2 [9]. Here, we report the partial characterization of 3 collagenous fractions obtained after limited pepsin treatment of foetal calf cartilage and isolated according to their solubility properties. The 1.2 M NaC1 fraction contains the la, 2t~ and 3a chains. The 2.0 M NaC1 and 3.0 M NaCl fractions contain at least 7 collagenous chains, which are related to the disulfide-bonded new chains enumerated above, but show some major differences, Antibodies against the 1.2 M and 2.0 M NaC1 fractions were raised in rabbits and their specificity tested by radioimmunoprecipitation. The localization of the corresponding collagenous chains was achieved by indirect immunofluorescence in epiphyseal proper and growth cartilage from foetal calf cartilage. 2. MATERIALS AND METHODS