Type II collagen is specific for cartilaginous tissues. It is essential for the normal embryonic development of the skeleton, for linear growth and for the ability of cartilage to resist compressive forces. Homotrimers of alpha 1(II) chains. Expressed in chondrogenic tissues in advance of chondrocyte differentiation. Expressed early in embryogenesis at 9.5 days both in the cranial mesenchyme destined for the chondrocranium, and the sclerotome of the somites, and at 12.5 days in the primordia of the hyoid and the laryngeal cartilage. Detected in all the chondrogenic tissues of the axial and appendicular skeleton until the onset of endochondral ossification. Expression also observed in non-chondrogenic tissues such as the notochord. Also expressed much later in the tail tendon, at 16.5-18.5 days. Transiently expressed in the heart at 9.5-12.5 days, the epidermis at 10.5-14.5 days, the calvarial mesenchyme at 12.5-16.5 days, the inner ear at 14.5 days and the fetal brain from 9.5-14.5 days. Within the neural tube, expression is localized to the proliferative ventricular cells of the forebrain and midbrain of 9.5-10.5 day embryos, and subsequently, restricted to the rhombencephalic basal plate, the ventricular layer of the hindbrain and the cervical spinal cord. The C-terminal propeptide, also known as COLFI domain, have crucial roles in tissue growth and repair by controlling both the intracellular assembly of procollagen molecules and the extracellular assembly of collagen fibrils. It binds a calcium ion which is essential for its function (By similarity). Contains mostly 4-hydroxyproline. Prolines at the third position of the tripeptide repeating unit (G-X-P) are 4-hydroxylated in some or all of the chains. Contains 3-hydroxyproline at a few sites. This modification occurs on the first proline residue in the sequence motif Gly-Pro-Hyp, where Hyp is 4-hydroxyproline. Lysine residues at the third position of the tripeptide repeating unit (G-X-Y) are 5-hydroxylated in some or all of the chains. O-glycosylated on hydroxylated lysine residues. The O-linked glycan consists of a Glc-Gal disaccharide. Defects in Col2a1 are the cause of a phenotype resembling human spondyloepiphyseal dysplasia congenita (sedc). Homozygous sedc mice can be identified at birth by their small size and shortened trunk. Adults have shortened noses, dysplastic vertebrae, femora and tibias, and retinoschisis and hearing loss. Belongs to the fibrillar collagen family. Truncated N-terminus.