Nissinen M, Vuolteenaho R, Boot-Handford R, Kallunki P, Tryggvason K
Biocenter, University of Oulu, Finland.
Biochem J. 1991 Jun 1;276 ( Pt 2)(Pt 2):369-79. doi: 10.1042/bj2760369.
cDNA clones for the human laminin A chain were isolated from libraries prepared from human gestational choriocarcinoma cell line (JAR) RNA. They cover approx. 8 kb from the 5'-end of the 9.5 kb mRNA coding for this protein. Our clones contain 94 nucleotide residues for the 5'-end untranslated region and 7885 nucleotide residues of coding sequence. The complete human laminin A chain contains a 17-amino acid-residue signal peptide and a 3058-residue A chain proper. The human laminin A chain has a distinct domain structure with numerous internal cysteine-rich repeats. The large globular domain G has five repeats, which have several conserved glycine and cysteine residues. Furthermore the A chain contains 20 internal cysteine-rich repeats present in tandem arrays in three separate clusters (domains IIIa, IIIb and V). Domain I + II has a predicted continuous alpha-helical structure characterized by heptad repeats and three domains (IVa, IVb and VI) are predicted to contain a number of beta-sheets and coiled-coil structures. Northern-blot analysis was used to study the laminin A chain expression in the JAR cell line, full-term placenta and newborn-human tissues (kidney, spleen, lung, heart muscle, psoas muscle and diaphragm muscle). The expression was detectable in newborn-human kidney and JAR cell line only. The overall amino acid sequence identity between human and mouse is 76%. The human chain has only one Arg-Gly-Asp (RGD) sequence, which is located in the long arm within domain G, whereas the single RGD sequence in the mouse chain is located in the short arm in domain IIIb. The degree of identity between the human laminin A chain sequence and the sequence available for merosin [Ehrig, Leivo, Argraves, Ruoslahti & Engvall (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 3264-3268] is about 41% and when conservative substitutions are included the degree of similarity is 54%.
从人妊娠绒毛膜癌细胞系（JAR）RNA构建的文库中分离出了人层粘连蛋白A链的cDNA克隆。它们覆盖了编码该蛋白的9.5 kb mRNA 5′端约8 kb的区域。我们的克隆包含5′端非翻译区的94个核苷酸残基和编码序列的7885个核苷酸残基。完整的人层粘连蛋白A链包含一个17个氨基酸残基的信号肽和一个由3058个残基组成的A链主体。人层粘连蛋白A链具有独特的结构域结构，有许多内部富含半胱氨酸的重复序列。大的球状结构域G有五个重复序列，其中有几个保守的甘氨酸和半胱氨酸残基。此外，A链包含20个内部富含半胱氨酸的重复序列，以串联阵列的形式存在于三个独立的簇（结构域IIIa、IIIb和V）中。结构域I + II具有预测的连续α螺旋结构，其特征为七肽重复序列，并且预测三个结构域（IVa、IVb和VI）包含许多β折叠和卷曲螺旋结构。采用Northern印迹分析研究层粘连蛋白A链在JAR细胞系、足月胎盘和新生儿组织（肾、脾、肺、心肌、腰大肌和膈肌）中的表达。仅在新生儿肾和JAR细胞系中可检测到表达。人与小鼠之间的总体氨基酸序列同一性为76%。人链只有一个精氨酸-甘氨酸-天冬氨酸（RGD）序列，位于结构域G内的长臂中，而小鼠链中的单个RGD序列位于结构域IIIb的短臂中。人层粘连蛋白A链序列与可获得的merosin序列[Ehrig、Leivo、Argraves、Ruoslahti和Engvall（1990年）美国国家科学院院刊87，3264 - 3268]之间的同一性程度约为41%，当包括保守取代时，相似性程度为54%。
