Type XII collagen interacts with type I collagen-containing fibrils, the COL1 domain could be associated with the surface of the fibrils, and the COL2 and NC3 domains may be localized in the perifibrillar matrix (By similarity). Could play a developmental role in regeneration. Trimer of identical chains each containing 190 kDa of non-triple-helical sequences. Expression starts at 3 days after amputation in cells of the basal layer of the wound epithelium. At day 10, expression is found in both the basal wound epithelial cells and the distal mesenchyme cells. At mid-bud and late-bud blastema stages, wound epithelium expression has decreased, whereas the mesenchyme remains strongly active in transcription and showed a tendency toward distal regionalization. Condensing cartilage shows no signal. Finally, at the late digit stage, expression becomes largely restricted to the perichondrium. The triple-helical tail is stabilized by disulfide bonds at each end. Prolines at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains. Belongs to the fibril-associated collagens with interrupted helices (FACIT) family.