Research for the primary structures of human vitamin D-binding proteins.

Gc蛋白是一种广泛存在于法律的医学和人类遗传学领域的人血清蛋白，在等电聚焦电泳上表现出由三个共显性基因（Gc 2、Gc 1F和Gc 1 S）控制的多种表型。这种蛋白质在血清或淋巴细胞上与肌动蛋白的亲和作用下具有重要的生物学功能，其特征称为维生素D结合蛋白（DBP）。1985年Yang通过对该cDNA的碱基序列分析，确定了DBP的一级结构。我们的目的是证实这个氨基酸序列推测的碱基序列，并阐明Gc亚型之间的氨基酸取代。通过盐法和色谱法从人血清中纯化DBPs。用高效液相色谱法分离了羧甲基化DBP的BrCN肽，并进一步用反相色谱法纯化了BrCN肽的酶促活性。通过氨基酸组成分析和氨基酸序列分析，确定了DBP（Gc 2）的一级结构。对携带Gc 1F或1 S的DBP进行序列分析。根据这些结果，DBP亚型之间的氨基酸取代是位置152处的GLY-GLU-Glu（Gc 2 -1F-1 S）、位置416处的ASP-ASP-GLU和位置420处的LYS-THR-THR。

Gc protein is one of human serum protein, which is widely available in the field of legal medicine and human genetics, and has several phenotypes controlled by three codominat genes (Gc2, Gc1F, and Gc1S) on isoelctric focusing electrophoresis. This protein, which is called vitamin D-binding protein (DBP) by the character, has important functions under the affinity of actin in serum or on lymphocyte. The primary structure of DBP, which many researchers in the world could not clarify in spite of many approaches, was determined through the base sequence analyses of that cDNA by Yang on 1985. We intended to confirm this amino acid sequence speculated by the base sequence and to elucidate the amino acid substitutions between Gc subtypes. DBPs were purified from human sera by salting and chromatography. The BrCN peptides of carboxymethylated DBP were separated by hiph-performance liquid chromatography, and further purification of the enzymatic digests of BrCN peptide was carried out on reversed-phase chromatography. We confirmed the primary structure of DBP (Gc2) by the amino acid composition analyses and the amino acid sequence analyses of these peptides. The sequence analysis of DBP carrying Gc1F or 1S was done by the same procedures. From these results, the amino acid substitutions between DBP subtypes are GLY-GLU-GlU (Gc2-1F-1S) at position 152, ASP-ASP-GLU at position 416, and LYS-THR-THR at position 420.