Wewer U M, Gerecke D R, Durkin M E, Kurtz K S, Mattei M G, Champliaud M F, Burgeson R E, Albrechtsen R
Laboratory of Molecular Pathology, University Institute of Pathological Anatomy, Copenhagen, Denmark.
Genomics. 1994 Nov 15;24(2):243-52. doi: 10.1006/geno.1994.1612.
Overlapping cDNA clones that encode the full-length human laminin beta 2 chain, formerly called the S chain, were isolated. The cDNA of 5680 nt contains a 5391-nt open reading frame encoding 1797 amino acids. At the amino terminus is a 32-amino-acid signal peptide that is followed by the mature beta 2 chain polypeptide of 1765 amino acids with a calculated molecular mass of 192,389 Da. The human beta 2 chain is predicted to have all of the seven structural domains typical of the beta chains of laminin, including the short cysteine-rich alpha region. The amino acid sequence of human beta 2 chain showed 86.1% sequence identity to the rat beta 2 chain, 50.0% to the human beta 1 chain, and 36.3% to the human beta 3 chain. The greatest sequence identity was in domains VI, V, and III. The sequence of a 24-amino-acid peptide fragment isolated from the beta 2 chain of laminin purified from human amniotic basement membrane matched the sequence predicted from the cDNA, confirming that the cDNA encodes human beta 2 laminin. The cDNA was used to assign the gene (LAMB2) to human chromosome 3p21 by in situ hybridization. It is not linked to genes for human laminin chains alpha 1, beta 1, and gamma 1 or other known laminin genes. Immunostaining showed that the beta 2 chain is localized to the smooth muscle basement membranes of the arteries, while the homologous beta 1 chain is confined to the subendothelial basement membranes. The beta 2 chain was found in the basement membranes of ovarian carcinomas but not colon carcinomas. These results indicate that the expression of the beta 2 chain gene is tightly regulated in normal human tissues and in disease.
分离出了编码全长人层粘连蛋白β2链（以前称为S链）的重叠cDNA克隆。5680 nt的cDNA包含一个5391 nt的开放阅读框，编码1797个氨基酸。在氨基末端是一个32个氨基酸的信号肽，其后是1765个氨基酸的成熟β2链多肽，计算分子量为192,389 Da。预计人β2链具有层粘连蛋白β链典型的所有七个结构域，包括富含半胱氨酸的短α区域。人β2链的氨基酸序列与大鼠β2链的序列同一性为86.1%，与人类β1链的序列同一性为50.0%，与人类β3链的序列同一性为36.3%。最大的序列同一性存在于结构域VI、V和III中。从人羊膜基底膜纯化的层粘连蛋白β2链中分离出的一个24个氨基酸的肽片段的序列与cDNA预测的序列匹配，证实该cDNA编码人β2层粘连蛋白。通过原位杂交，该cDNA被用于将基因（LAMB2）定位到人类染色体3p21。它与人类层粘连蛋白链α1、β1和γ1的基因或其他已知的层粘连蛋白基因没有连锁关系。免疫染色显示，β2链定位于动脉的平滑肌基底膜，而同源的β1链局限于内皮下基底膜。在卵巢癌的基底膜中发现了β2链，但在结肠癌中未发现。这些结果表明，β2链基因的表达在正常人体组织和疾病中受到严格调控。
