Plays a role in virulence and host-pathogen interactions. Mediates binding to human platelets via interaction with the human cell surface glycoprotein GP1BA (PubMed:21765814). Plays a positive role in biofilm formation, possibly by self-association via the basic region (BR) (PubMed:20714350). Both SSR domains in the unglycosylated protein bind to Asp2 and Asp3; glycosylated protein binds less well. Interacts with the human cell surface glycoprotein GP1BA. Exported by the accessory SecA2/SecY2 protein translocation apparatus. Has a short and long Ser-rich region with a basic region between them. The SRR domains themselves are comprised of inexact repeats of SASESASTSASV. SSR1 has 6 repeats, SSR2 has 200. The Ser-rich regions are both glycosylated. The basic region (BR) binds to whole cell lysates of wild-type but not bacteria deleted of this gene; it also recognizes whole cell lysates of S.aureus strain ISP479C probably via SraP, but not lysates of S.pneumoniae TIGR4 (PubMed:20714350). The predicted pI of the basic region is 9.51 (PubMed:19202081). Proteolytically cleaved by a metalloprotease. Both SSR1 and SSR2 domains are glycosylated (Probable). A truncated derivative (residues 1-2062) contains 105 nmol per nmol of protein, suggesting at least 10% of the apparent molecular weight is due to carbohydrates (PubMed:14729688). Glucose and N-acetylglucosamine are present in a ratio of 30:73 residues per truncated polypeptide, as well as minor amounts of galactose and N-acetylgalactosamine (PubMed:14729688). Glycosylation occurs intracellularly in the Ser-rich regions SSR1 and SSR2 (PubMed:14729688, PubMed:15489421). Glycosylation of SSR2 domain may be required to prevent aggregation of GspB (Probable). It is probable that most of the Ser residues in SSR1 and SSR2 are O-GlcNAcylated. Sequential glycosylation by sugar transferases are able to generate complex sugar polymorphisms (By similarity). Loss of adherence to human platelet cells (PubMed:12010500). Decrease in early biofilm formation (PubMed:20714350). S.gordonii, a commensal oral cavity bacteria, is among the bacteria most frequently identified as being the primary etiological agents of subacute infective endocarditis (found in 13% of cases). Belongs to the serine-rich repeat protein (SRRP) family.