Li Dongmei, Graham Lloyd D
CSIRO Molecular & Health Technologies, Sydney Laboratory, P.O.Box 184, North Ryde, NSW 1670, Australia.
Comp Biochem Physiol B Biochem Mol Biol. 2007 Oct;148(2):192-200. doi: 10.1016/j.cbpb.2007.05.009. Epub 2007 May 31.
The organic fraction of epiphragm mucus from the snail Cernuella virgata (Mollusca: Helicidae) consists predominantly of protein (17-23 dry wt.%) rather than carbohydrate (< or =0.4-2.0 dry wt.%), and the former underpins epiphragm membrane structure. The major protein ('epiphragmin') has an apparent molecular mass of approximately 86 kDa and is encoded by a cDNA (Genbank accession EF602752) which specifies a secreted protein of 81.2 kDa. The central region of the epiphragmin polypeptide is a coiled coil-forming region which is homologous to part of AglZ, a bacterial filament-forming protein. Coiled coil-driven self-assembly of epiphragmin probably underpins the formation of sheets in epiphragm membranes and the ability of epiphragm mucus to serve as an adhesive. The C-terminal region of epiphragmin is a fibrinogen-related domain (FReD) that is homologous to the fibrinogen-related proteins (FREPs) found in the hemolymph of freshwater snails. The material properties of epiphragm membranes resemble those of bovine ligament elastin. Wooden lap-joints bonded by rehydrated epiphragm fragments developed dry shear strength values of 1.4+/- 0.1 MPa.
来自维氏堇蜗牛（软体动物：旋蜗牛科）隔膜黏液的有机成分主要由蛋白质构成（占干重的17 - 23%），而非碳水化合物（≤0.4 - 2.0干重%），且前者支撑着隔膜的膜结构。主要蛋白质（“隔膜蛋白”）的表观分子量约为86 kDa，由一个cDNA（基因库登录号EF602752）编码，该cDNA编码一种81.2 kDa的分泌蛋白。隔膜蛋白多肽的中央区域是一个形成卷曲螺旋的区域，与细菌丝状形成蛋白AglZ的一部分同源。由卷曲螺旋驱动的隔膜蛋白自组装可能是隔膜膜中片层形成以及隔膜黏液具有黏附能力的基础。隔膜蛋白的C端区域是一个纤维蛋白原相关结构域（FReD），与淡水蜗牛血淋巴中发现的纤维蛋白原相关蛋白（FREPs）同源。隔膜膜的材料特性类似于牛韧带弹性蛋白。用复水后的隔膜碎片粘结的木制搭接接头的干抗剪强度值为1.4±0.1 MPa。
