The core protein (proteoglycan 1, 153 aa) of the proteoglycan that is found in the storage granules of platelets, leucocytes and mast cells. The protein has 24 serine-glycine repeats to which various (~15) glycosaminoglycan chains, usually heparin or highly sulphated chondroitin sulphate, are attached. The negative charge on the proteoglycan is probably important for packing positively charged proteases, histamine, etc. within the granules.
Subjects: Medicine and Health — Chemistry.