Parmentier M, Lefort A
Institut de Recherche Interdisciplinaire en Biologie Humaine et Nucléaire, Université Libre de Bruxelles, Belgium.
Eur J Biochem. 1991 Feb 26;196(1):79-85. doi: 10.1111/j.1432-1033.1991.tb15788.x.
Calbindin D28k and calretinin are two closely related intracellular calcium-binding proteins belonging to the troponin C superfamily. Calbindin is known to be involved in the vitamin-D-dependent calcium absorption through intestinal and renal epithelia, while the function of neuronal calbindin and calretinin is poorly understood. Using antibodies directed against chick intestinal calbindin D28k, human calretinin cDNA clones were isolated from brain cDNA libraries. The sequence of the calretinin cDNA revealed an open reading frame of 271 codons coding for a protein of 31,520 Da, and sharing 58% identical residues with human calbindin D28k. Calretinin contains five presumably active and one presumably inactive calcium-binding domains. Comparison with the partial sequences available for chick and guinea pig calretinins revealed that the protein is highly conserved in evolution (evolutionary rate: 0.27 x 10(-9) amino acid-1 year-1). The calretinin message was detected in the brain, while absent from heart muscle, kidney, liver, lung, spleen, stomach and thyroid gland. Recombinant calretinin was expressed in Escherichia coli, and the calcium-binding properties were confirmed on both the natural and the recombinant proteins. Part of the human gene coding for calretinin was isolated and the region corresponding to the promoter and the first exon was sequenced.
钙结合蛋白D28k和钙视网膜蛋白是两种密切相关的细胞内钙结合蛋白，属于肌钙蛋白C超家族。已知钙结合蛋白参与维生素D依赖的钙通过肠道和肾上皮的吸收，而神经元钙结合蛋白和钙视网膜蛋白的功能却知之甚少。利用针对鸡肠道钙结合蛋白D28k的抗体，从脑cDNA文库中分离出人类钙视网膜蛋白cDNA克隆。钙视网膜蛋白cDNA的序列显示有一个271个密码子的开放阅读框，编码一个31520 Da的蛋白质，与人类钙结合蛋白D28k有58%的相同残基。钙视网膜蛋白含有五个可能有活性和一个可能无活性的钙结合结构域。与鸡和豚鼠钙视网膜蛋白的部分序列比较表明，该蛋白在进化过程中高度保守（进化速率：0.27×10⁻⁹氨基酸⁻¹年⁻¹）。在脑中检测到钙视网膜蛋白信息，而在心肌、肾、肝、肺、脾、胃和甲状腺中未检测到。重组钙视网膜蛋白在大肠杆菌中表达，并在天然蛋白和重组蛋白上证实了其钙结合特性。分离出了人类编码钙视网膜蛋白的部分基因，并对与启动子和第一个外显子对应的区域进行了测序。
