Low-molecular-weight_chromium-binding_substance
Low-molecular-weight chromium-binding substance (LMWCr; also known as chromodulin) is an oligopeptide that seems to transport chromium in the body.[1] It consists of four amino acid residues; aspartate, cysteine, glutamate, and glycine, bonded with four (Cr3+) centers. It interacts with the insulin receptor, by prolonging kinase activity through stimulating the tyrosine kinase pathway, thus leading to improved glucose absorption.[2][3] and has been confused with glucose tolerance factor.[4]
The exact mechanisms underlying this process are currently unknown.[3] Evidence for the existence of this protein comes from the fact that the removal of 51Cr in the blood exceeds the rate of 51Cr formation in the urine.[5] This indicates that the transport of Cr3+ must involve an intermediate (i.e. chromodulin) and that Cr3+ is moved from the blood to tissues in response to increased levels of insulin.[3][5] Subsequent protein isolations in rats, dogs, mice and cows have shown the presence of a similar substance, suggesting that it is found extensively in mammals.[6][7][8] This oligopeptide is small, having a molecular weight of around 1 500 g/mol and the predominant amino acids present are aspartic acid, glutamic acid, glycine, and cysteine.[6][7][8] Despite recent efforts to characterize the exact structure of chromodulin, it is still relatively unknown.[3][9]