Cartilage Intermediate Layer Protein 2 (CILP2)

The deduced CILP2 protein shares 50.6% identity with CILP1, and both proteins have a central furin (FUR) endoprotease consensus cleavage site predicted to cause release of N- and C-terminal peptides.The N-terminal halves of CILP1 and CILP2 contain a thrombospondin type-1 repeat and an immunoglobulin C2-type domain, but the N-terminal half of CILP2 lacks the putative aldehyde dehydrogenase cysteine active site and the ATP-binding site found in CILP1. RT-PCR detected both CILP1 and CILP2 in cultured normal hyaline cartilage articular chondrocytes, but not in osteoblasts, fibroblasts, or vascular smooth muscle cells. Only CILP1 was detected in normal knee meniscal fibrocartilage chondrocytic cells.