Bernier S M, Utani A, Sugiyama S, Doi T, Polistina C, Yamada Y
Laboratory of Development of Biology, National Institute of Dental Research, Bethesda, Maryland, USA.
Matrix Biol. 1995 Feb;14(6):447-55. doi: 10.1016/0945-053x(95)90002-0.
Laminins are a family of heterotrimeric glycoproteins specific to basement membranes. Laminin-2, consisting of alpha 2, beta 1 and gamma 1 chains, was originally identified in the basement membranes of skeletal muscle and peripheral nerve. We have isolated and sequenced the full-length cDNA for the mouse laminin alpha 2 chain. Four overlapping clones spanning 9,330 bp encode a predicted polypeptide of 3,106 amino acids having a calculated molecular mass of 390 kDa including a 23-amino-acid signal peptide. The amino acid sequence of the alpha 2 chain shares a 45.9% identify with that of the alpha 1 chain. Similar to the structure of the alpha 1 chain, the alpha 2 chain consists of several domains beginning at the N-terminus with three globular domains alternating with three epidermal growth factor-like domains followed by two alpha-helical domains and a C-terminal globular domain. The most N-terminal globular domain is highly conserved (77.3% identity) between the alpha 2 and alpha 1 chains, whereas the alpha-helical domains have low homology (30.3% identity). Northern blot and ribonuclease protection analysis revealed expression of mRNA for the alpha 2 chain in heart, kidney, liver, skin, lung and skeletal muscle of newborn mice. such a tissue distribution suggests a role for the alpha 2 chain and, consequently, laminin-2 or -4 not only in the organization and the function of nerve and muscle tissue but possibly also in the mesenchymal components of certain tissues.
层粘连蛋白是一类特异存在于基底膜的异源三聚体糖蛋白。层粘连蛋白-2由α2、β1和γ1链组成，最初在骨骼肌和外周神经的基底膜中被鉴定出来。我们已经分离并测序了小鼠层粘连蛋白α2链的全长cDNA。四个重叠克隆，跨度为9330 bp，编码一个预测的由3106个氨基酸组成的多肽，计算分子量为390 kDa，包括一个23个氨基酸的信号肽。α2链的氨基酸序列与α1链的氨基酸序列有45.9%的同源性。与α1链的结构相似，α2链由几个结构域组成，从N端开始，有三个球状结构域与三个表皮生长因子样结构域交替出现，接着是两个α螺旋结构域和一个C端球状结构域。α2链和α1链之间最N端的球状结构域高度保守（同源性为77.3%），而α螺旋结构域的同源性较低（同源性为30.3%）。Northern印迹和核糖核酸酶保护分析显示，新生小鼠的心脏、肾脏、肝脏、皮肤、肺和骨骼肌中存在α2链mRNA的表达。这种组织分布表明α2链，进而层粘连蛋白-2或-4不仅在神经和肌肉组织的组织和功能中起作用，而且可能在某些组织的间充质成分中也起作用。
