Utani A, Kopp J B, Kozak C A, Matsuki Y, Amizuka N, Sugiyama S, Yamada Y
Laboratory of Developmental Biology, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Lab Invest. 1995 Mar;72(3):300-10.
Kalinin, an anchoring filament-associated protein, is a member of the laminin family which is believed to play a role in the attachment of particular epithelial cells to the basement membrane.
A newborn mouse lung cDNA library was screened under low stringency conditions using as a probe a murine laminin beta 1 chain cDNA, an approach designed to identify novel laminin beta 1 chain homologs.
We have identified a novel cDNA sequence comprising 4049 base pairs, with an open reading frame that potentially codes for 1168 amino acids, including a presumptive signal peptide. The gene was mapped to mouse chromosome 1. The amino acid sequence is homologous to laminin beta 1 and beta 2 chains, but is distinguished from these molecules by having a truncated short arm region. The sequence has considerable similarity to the human kalinin B1 chain (laminin beta 3), suggesting that it is murine beta 3 chain. Northern blot analysis demonstrated a single 4.0-kilobase species in the mouse newborn skin, lung, and Pam 212 cells. Immunolocalization studies using the 14-day embryo and adult mouse tissues demonstrated that the murine beta 3 chain is located at the dermal-epidermal junction of the skin and the basement membrane of the oral mucosa, oropharynx, and upper portions of the tracheobronchial tree. In situ hybridization studies of the mammary gland showed that the beta 3 mRNA chain was produced by the epithelial cells of the gland but not by the mesenchymal cells. Western blotting under nonreducing conditions using the antibody to beta 3 chain detected molecules of 400 and 440 kilodaltons (kDa) in the conditioned medium of human foreskin keratinocytes, A431 cells, and Pam 212 cells. Western blotting under reducing conditions detected only a single 140-kDa species, suggesting that beta 3 chain is present within disulfide-linked complexes. This 140-kDa species was contained in the kalinin complex immunoprecipitated by anti-kalinin B2 (laminin gamma 2) antibody from the conditioned medium of HT1080 cells, suggesting that both the beta 3 and gamma 2 chains are present in the multimeric complex.
Murine laminin beta 3 chain shows considerable homology to the human homolog and has a tightly restricted tissue distribution, confined to the basement membrane of cells in contact with the external environment. In vitro studies indicate that the beta 3 chain participates in trimer formation with the gamma 2 chain and possibly with other laminin chains as well.
角蛋白是一种与锚定丝相关的蛋白质，属于层粘连蛋白家族，据信在特定上皮细胞与基底膜的附着过程中发挥作用。
以小鼠层粘连蛋白β1链cDNA为探针，在低严谨条件下筛选新生小鼠肺cDNA文库，该方法旨在鉴定新的层粘连蛋白β1链同源物。
我们鉴定出一个新的cDNA序列，由4049个碱基对组成，具有一个开放阅读框，可能编码1168个氨基酸，包括一个推测的信号肽。该基因定位于小鼠1号染色体。其氨基酸序列与层粘连蛋白β1和β2链同源，但通过具有截短的短臂区域而与这些分子有所区别。该序列与人类角蛋白B1链（层粘连蛋白β3）有相当的相似性，表明它是小鼠β3链。Northern印迹分析显示在新生小鼠皮肤、肺和Pam 212细胞中存在单一的4.0千碱基条带。使用14天胚胎和成年小鼠组织进行的免疫定位研究表明，小鼠β3链位于皮肤的真皮 - 表皮交界处以及口腔黏膜、口咽和气管支气管树上部的基底膜处。乳腺的原位杂交研究表明，β3 mRNA链由腺体的上皮细胞产生，而间充质细胞不产生。在非还原条件下使用抗β3链抗体进行的Western印迹分析在人包皮角质形成细胞、A431细胞和Pam 212细胞的条件培养基中检测到400和440千道尔顿（kDa）的分子。在还原条件下进行的Western印迹分析仅检测到单一的140-kDa条带，表明β3链存在于二硫键连接的复合物中。这种140-kDa条带包含在由抗角蛋白B2（层粘连蛋白γ2）抗体从HT1080细胞条件培养基中免疫沉淀的角蛋白复合物中，表明β3和γ2链都存在于多聚体复合物中。
小鼠层粘连蛋白β3链与人类同源物有相当的同源性，并且具有严格受限的组织分布，局限于与外部环境接触的细胞的基底膜。体外研究表明，β3链与γ2链以及可能与其他层粘连蛋白链一起参与三聚体的形成。
