Pikkarainen T, Eddy R, Fukushima Y, Byers M, Shows T, Pihlajaniemi T, Saraste M, Tryggvason K
J Biol Chem. 1987 Aug 5;262(22):10454-62.
We report the isolation and characterization of six overlapping cDNA clones that provide the first and complete amino acid sequence of the human laminin B1 chain. The cDNA clones cover 5613 nucleotides with 5358 nucleotides in an open reading frame encoding 1786 amino acids, including a 21-residue signal peptide-like sequence. Sequence analysis demonstrated the presence of two types of internal homology repeats that were found in clusters within the polypeptide chain. The type A repeats contain about 50 amino acids of which 8 are cysteine. These repeats are present in two clusters toward the NH2-terminal end of the chain and are separated from each other by about 220 amino acids. The two clusters contain five and eight consecutive repeats each. There are two copies of consecutive type B repeats of about 40 amino acids close to the COOH-terminal end. Computer analysis of the amino acid sequence of the B1 chain revealed the presence of structurally distinct domains that contain cysteine-rich repeats, globular regions, and helical structures. Using somatic cell hybrid methodology and in situ hybridization to metaphase chromosomes it was established that the human laminin B1 gene (LAMB1) is located in the q22 region of chromosome 7.
我们报道了六个重叠cDNA克隆的分离与鉴定，这些克隆提供了人层粘连蛋白B1链的首个完整氨基酸序列。这些cDNA克隆覆盖5613个核苷酸，其中5358个核苷酸处于一个开放阅读框中，编码1786个氨基酸，包括一个21个残基的信号肽样序列。序列分析表明存在两种类型的内部同源重复序列，它们在多肽链中呈簇状分布。A 型重复序列包含约50个氨基酸，其中8个是半胱氨酸。这些重复序列在靠近链NH2末端的两个簇中存在，彼此相隔约220个氨基酸。这两个簇分别包含五个和八个连续的重复序列。在靠近COOH末端有两个连续的约40个氨基酸的B型重复序列拷贝。对B1链氨基酸序列的计算机分析揭示了存在结构上不同的结构域，这些结构域包含富含半胱氨酸的重复序列、球状区域和螺旋结构。利用体细胞杂交方法和中期染色体原位杂交技术确定，人层粘连蛋白B1基因（LAMB1）位于7号染色体的q22区域。
