C-type lectin-like domain (CTLD) of the type found in the tetranectin (TN), cartilage derived C-type lectin (CLECSF1), and stem cell growth factor (SCGF)
CLECT_tetranectin_like: C-type lectin-like domain (CTLD) of the type found in the tetranectin (TN), cartilage derived C-type lectin (CLECSF1), and stem cell growth factor (SCGF). CTLD refers to a domain homologous to the carbohydrate-recognition domains (CRDs) of the C-type lectins. TN binds to plasminogen and stimulates activation of plasminogen, playing a key role in the regulation of proteolytic processes. The TN CTLD binds two calcium ions. Its calcium free form binds to various kringle-like protein ligands. Two residues involved in the coordination of calcium are critical for the binding of TN to the fourth kringle (K4) domain of plasminogen (Plg K4). TN binds the kringle 1-4 form of angiostatin (AST K1-4). AST K1-4 is a fragment of Plg, commonly found in cancer tissues. TN inhibits the binding of Plg and AST K1-4 to the extracellular matrix (EMC) of endothelial cells and counteracts the antiproliferative effects of AST K1-4 on these cells. TN also binds the tenth kringle domain of apolipoprotein (a). In addition, TN binds fibrin and complex polysaccharides in a Ca2+ dependent manner. The binding site for complex sulfated polysaccharides is N-terminal to the CTLD. TN is homotrimeric; N-terminal to the CTLD is an alpha helical domain responsible for trimerization of monomeric units. TN may modulate angiogenesis through interactions with angiostatin and coagulation through interaction with fibrin. TN may play a role in myogenesis and in bone development. Mice having a deletion in the TN gene exhibit a kyphotic spine abnormality. TN is a useful prognostic marker of certain cancer types. CLECSF1 is expressed in cartilage tissue, which is primarily intracellular matrix (ECM), and is a candidate for organizing ECM. SCGF is strongly expressed in bone marrow and is a cytokine for primitive hematopoietic progenitor cells.