Zhao Hua, Sun Chengjun, Stewart Russell J, Waite J Herbert
Molecular, Cell, and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA.
J Biol Chem. 2005 Dec 30;280(52):42938-44. doi: 10.1074/jbc.M508457200. Epub 2005 Oct 14.
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.
加州沙堡蠕虫（Phragmatopoma californica）的矿化管由外源矿物质颗粒（沙子、贝壳等）构成，这些颗粒通过蠕虫胸部“造管器官”分泌的一种黏合剂黏合在一起。这种黏合剂是三种高极性蛋白质的交联混合物。Pc-1（18 kDa）和Pc-2（21 kDa）的完整序列是根据先前报道的肽序列推导出来的cDNA（Waite, J. H., Jensen, R., and Morse, D. E. (1992) Biochemistry 31, 5733 - 5738）。这两种蛋白质都是碱性的（pI约为10），并呈现富含甘氨酸的肽重复序列。Pc-1和Pc-2中的共有重复序列分别为VGGYGYGGKK（15次）和HPAVXHKALGGYG（8次），其中X表示一个中间的非重复序列，Y被修饰为3,4 - 二羟基苯丙氨酸（多巴）。第三种蛋白质Pc-3从黏合剂中推导出来，约80摩尔%为磷酸丝氨酸/丝氨酸，其cDNA是通过利用多聚丝氨酸重复序列的存在而获得的。Pc-3由至少七个变体组成，丝氨酸含量为60 - 90摩尔%，其中大部分在黏合剂中被磷酸化。Pc-1、Pc-2和Pc-3都含有半胱氨酸，其中一些在固化过程中反应形成5 - S - 半胱氨酰多巴交联。
