Kono M, Hayashi N, Samata T
Laboratory for Cell Biology, Department of Environmental Health, Azabu University, 1-17-71 Fuchinobe, Sagamihara-shi, Kanagawa, 229-8501, Japan.
Biochem Biophys Res Commun. 2000 Mar 5;269(1):213-8. doi: 10.1006/bbrc.2000.2274.
We have cloned the cDNAs that encode two kinds of molluscan shell matrix proteins, namely N66 and N14, in the nacreous layer of Pinctada maxima. N66 is composed of carbonic anhydrase-like and repeat domains, as described for nacrein (1) in the pearls of P. fucata. N14 is homologous to N16, recently found in the nacreous layer of P. fucata (2) and is characterized by high proportions of Gly, Tyr, and Asn together with NG repeat sequences. The molecular weights of these proteins were estimated as 59,814 and 13,734 Da, respectively. Structural differences were clearly indicated in the alignment and length of the repeat sequences of the sets of the homogeneous proteins (N66/nacrein and N14/N16). The longer repeat sequences of N66 and N14 may be responsible for P. maxima's excellent property of calcification. The in vitro crystallization experiments revealed that the mixture of N66 and N14 could induce platy aragonite layers highly similar to the nacreous layer, once adsorbed onto the membrane of the water-insoluble matrix.
我们已经克隆了编码两种软体动物贝壳基质蛋白的cDNA，即大珠母贝珍珠层中的N66和N14。N66由碳酸酐酶样结构域和重复结构域组成，就像合浦珠母贝珍珠中的珍珠质（1）一样。N14与最近在合浦珠母贝珍珠层中发现的N16同源（2），其特征是甘氨酸、酪氨酸和天冬酰胺的比例较高，以及NG重复序列。这些蛋白质的分子量分别估计为59,814和13,734道尔顿。在同源蛋白质组（N66/珍珠质和N14/N16）的重复序列比对和长度上，结构差异明显。N66和N14较长的重复序列可能是大珠母贝卓越钙化特性的原因。体外结晶实验表明，N66和N14的混合物一旦吸附到水不溶性基质膜上，就能诱导出与珍珠层高度相似的片状文石层。
