8.A.74.1.6
SPARC, with 303 aas and 1 N-terminal TMS. It may regulate cell growth through interactions with the extracellular matrix and cytokines. It binds calcium and copper, several types of collagen, albumin, thrombospondin, PDGF and cell membranes. There are two calcium binding sites; an acidic domain that binds 5 to 8 Ca²⁺ with a low affinity and an EF-hand loop that binds a Ca²⁺ ion with a high affinity. In an oxidative stress environment, neovascularization within a tumor occurs with structural deterioration and decreased perfusion capacity. One of the main regulatory mechanisms is the migration of extracellular SPARC from the endothelium to intracellular compartments via Caveolin-1 carriers (Zhao et al. 2023).