Upper diagram: The domains identified in GspB are characteristic of the SRR glycoprotein family. SP, signal peptide; AST, accessory Sec transport domain; SRR1 and SRR2, serine-rich repeat regions 1 and 2, respectively; BR, ligand binding region; CWA, cell wall anchoring domain (including an LPxTG motif).
Lower diagram: Amino-terminal sequence of the SRR glycoproteins from S. gordonii (GspB), S. parasangunis (Fap1), S. aureus (SraP), and P. acidilactici (SRRpp).