{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T10:25:49Z","timestamp":1789727149389,"version":"4.0.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"21","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1992,11]]},"abstract":"<jats:p>Group B Streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis in the United States. The surface-associated C protein alpha antigen of GBS is thought to have a role in both virulence and immunity. We previously cloned the C protein alpha antigen structural gene (named bca for group B, C protein, alpha) into Escherichia coli. Western blots of both the native alpha antigen and the cloned gene product demonstrate a regularly laddered pattern of heterogeneous polypeptides. The nucleotide sequence of the bca locus reveals an open reading frame of 3060 nucleotides encoding a precursor protein of 108,705 Da. Cleavage of a putative signal sequence of 41 amino acids yields a mature protein of 104,106 Da. The 20,417-Da N-terminal region of the alpha antigen shows no homology to previously described protein sequences and is followed by a series of nine tandem repeating units that make up 74% of the mature protein. Each repeating unit is identical and consists of 82 amino acids with a molecular mass of 8665 Da, which is encoded by 246 nucleotides. The size of the repeating units corresponds to the observed size differences in the heterogeneous ladder of alpha C proteins expressed by GBS. The C-terminal region of the alpha antigen contains a membrane anchor domain motif that is shared by a number of Gram-positive surface proteins. The large region of identical repeating units in bca defines protective epitopes and may play a role in generating phenotypic and genotypic diversity of the alpha antigen.<\/jats:p>","DOI":"10.1073\/pnas.89.21.10060","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T08:11:21Z","timestamp":1149063081000},"page":"10060-10064","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":124,"title":["Large, identical, tandem repeating units in the C protein alpha antigen gene, bca, of group B streptococci."],"prefix":"10.1073","volume":"89","author":[{"given":"J L","family":"Michel","sequence":"first","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L C","family":"Madoff","sequence":"additional","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K","family":"Olson","sequence":"additional","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D E","family":"Kling","sequence":"additional","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D L","family":"Kasper","sequence":"additional","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"F M","family":"Ausubel","sequence":"additional","affiliation":[{"name":"Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1992,11]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.89.21.10060","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T13:49:40Z","timestamp":1649857780000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.89.21.10060"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1992,11]]},"references-count":0,"journal-issue":{"issue":"21","published-print":{"date-parts":[[1992,11]]}},"alternative-id":["10.1073\/pnas.89.21.10060"],"URL":"https:\/\/doi.org\/10.1073\/pnas.89.21.10060","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1992,11]]},"assertion":[{"value":"1992-11-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}