Crittenden S L, Rutishauser U, Lilien J
University of Wisconsin, Department of Zoology, Madison 53706.
Proc Natl Acad Sci U S A. 1988 May;85(10):3464-8. doi: 10.1073/pnas.85.10.3464.
By using an immunological and peptide mapping approach two calcium-dependent cell-cell adhesion molecules (calCAMs) in the embryonic chicken are compared. A third closely related molecule is identified and compared to the two calCAMs. One of the calCAMs appears to be identical to the previously identified adhesion molecule N-cadherin, originally identified in chicken retina and localized to neural tissues. The second is the same as L-CAM, originally identified in chicken liver but localized to a variety of epithelial tissues. The third, also found in liver, is similar to L-CAM but is much closer in structure to N-cadherin. It is, however, immunologically distinct from N-cadherin. We therefore refer to this newly identified molecule as CRM-L for cadherin-related molecule in liver. CRM-L, N-cadherin, and L-CAM are all cell-surface proteins with a similar stability to tryptic digestion in the presence of calcium. CRM-L has the same molecular mass and isoelectric point as N-cadherin but is distinct from L-CAM in these properties. Two-dimensional peptide maps of complete tryptic digests reveal that CRM-L shares 69% of its peptides with N-cadherin and 20% with L-CAM. On the basis of these data, we suggest that there are at least two distinguishable types of calCAMs in the chicken embryo: one represented by the closely related molecules N-cadherin and CRM-L, and another represented by L-CAM.
通过采用免疫学和肽图谱分析方法，对胚胎鸡体内的两种钙依赖性细胞间粘附分子（calCAMs）进行了比较。鉴定出了第三种与之密切相关的分子，并将其与这两种calCAMs进行比较。其中一种calCAM似乎与先前鉴定出的粘附分子N-钙粘蛋白相同，N-钙粘蛋白最初在鸡视网膜中发现，并定位于神经组织。第二种与L-CAM相同，L-CAM最初在鸡肝脏中发现，但定位于多种上皮组织。第三种同样在肝脏中发现，与L-CAM相似，但在结构上与N-钙粘蛋白更为接近。然而，它在免疫学上与N-钙粘蛋白不同。因此，我们将这种新鉴定出的分子称为肝脏中与钙粘蛋白相关的分子CRM-L。CRM-L、N-钙粘蛋白和L-CAM都是细胞表面蛋白，在有钙存在的情况下，它们对胰蛋白酶消化的稳定性相似。CRM-L与N-钙粘蛋白具有相同的分子量和等电点，但在这些特性上与L-CAM不同。完整胰蛋白酶消化产物的二维肽图谱显示，CRM-L与N-钙粘蛋白有69%的肽段相同，与L-CAM有20%的肽段相同。基于这些数据，我们认为在鸡胚胎中至少存在两种可区分的calCAMs类型：一种由密切相关的分子N-钙粘蛋白和CRM-L代表，另一种由L-CAM代表。
