title: Cement proteins of the tube-building polychaete Phragmatopoma californica.
abstract: The mineralized tube of the sandcastle worm Phragmatopoma californica is made from exogenous mineral particles (sand, shell, etc.) glued together with a cement secreted from the "building organ" on the thorax of the worm. The glue is a cross-linked mixture of three highly polar proteins. The complete sequences of Pc-1 (18 kDa) and Pc-2 (21 kDa) were deduced from cDNAs derived from previously reported peptide sequences (Waite, J. H., Jensen, R., and Morse, D. E. (1992) Biochemistry 31, 5733-5738). Both proteins are basic (pI approximately 10) and exhibit Gly-rich peptide repeats. The consensus repeats in Pc-1 and -2 are VGGYGYGGKK (15 times), and HPAVXHKALGGYG (eight times), respectively, in which X denotes an intervening nonrepeated sequence and Y is modified to 3,4-dihydroxyphenyl-l-alanine (Dopa). The third protein, Pc-3, was deduced from the cement to be about 80 mol % phosphoserine/serine, and the cDNA was obtained by exploiting the presence of poly-serine repeats. Pc-3 consists of a family of at least seven variants with 60-90 mol % serine most of which is phosphorylated in the cement. Pc-1, -2, and -3 contain cysteine some of which reacts to form 5-S-cysteinyl-Dopa cross-links during the setting process.
authors.affiliation: Molecular, Cell, and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhao
authors.forename: Chengjun
authors.initials: C
authors.lastname: Sun
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Stewart
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011077:Polychaeta / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013997:Time Factors
chemical_list: D000596:Amino Acids; D003432:Cross-Linking Reagents; D018076:DNA, Complementary; D010455:Peptides; D012694:Serine; D003545:Cysteine