PDGF binds to extracellular matrix proteins

The long splice version of the PDGF-A chain as well as the COOH-terminal part of the PDGF-B precursor contain C-terminal protein motifs that confer retention of the secreted factors. In both the PDGF A- and B-chains, exon 6 encodes a basic sequence that mediates interaction with components of the extracellular matrix. PDGF binds to various types of collagens, thrombospondin and osteopontin; however, the major component of the matrix involved in PDGF binding is likely to be haparan sulphate. The negatively charged sulfate groups on the disaccharide building blocks of heparan sulfate (HS) polysaccharide chains provide binding sites for positively charged amino acid sequence motifs. <br>The precursor of the B-chain may be retained in the matrix; after maturation when the COOH-terminal retention sequence has been cleaved off, the molecule may become more diffusible.

PDGF-A链的长拼接版本及其前体蛋白的羧基端部分均含有C端蛋白基序，这些基序赋予分泌因子的保留能力。在PDGF A-链和B链中，外显子6编码的碱性序列介导与细胞外基质成分的相互作用。PDGF可与多种类型的胶原蛋白、血栓烷和骨桥蛋白结合；然而，在PDGF结合中起主要作用的基质成分可能是肝素硫酸酯。肝素硫酸酯（HS）多糖链的二糖构建块上的负电荷硫酸基团为带正电荷的氨基酸序列基序提供了结合位点。B链的前体蛋白可能被基质保留；在成熟过程中，当羧基端保留序列被切除后，该分子可能变得更加扩散。