... Among the protein structural/functional modules, short (of 3 to 10 amino acid residues) linear peptide motifs of proteins have been shown to participate in receptor binding (RGD), secretion and transportation of proteins from and to endoplasmic reticulum (KDEL and HDEL), SH3-domain-binding and cell signaling (PXXP motif) and so on [3, 4]. ... Additionally, all PSGs contain integrin-binding tripeptide RGD (residues 127-129). ... Asterisks show amino acid residues that participate in receptor binding....