Rajaraman R
Department of Medicine and Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.
Exp Cell Res. 1993 Mar;205(1):25-31. doi: 10.1006/excr.1993.1053.
Integrins are heterodimeric cell surface receptors involved in cell adhesion to extracellular matrix proteins and in cell-cell interactions. RGD peptide-specific integrin subunit alpha v and its associated beta subunits were isolated by GRGDSPK-Sepharose affinity chromatography. Using Western blot and immunoprecipitation techniques, the nature of this integrin complexity in the avian system was studied in comparison with that of the human system. As found in human cell systems, in chicken embryo fibroblasts the integrin alpha v subunit is associated with both the 90-kDa beta 3 and the 110-kDa beta 1-like subunits with high specific binding to RGD peptides. Furthermore, immunoprecipitation studies revealed the presence of an unidentified 120-kDa subunit and an 85-kDa beta 5 subunit associated with the alpha v subunit in these cells. No qualitative differences were observed in the beta subunit profile associated with alpha v, as a function of the proliferating nonconfluent or nonproliferating confluent states of the embryonic fibroblast cultures. In adult chicken gizzard, a 110-kDa beta 1-like subunit and a 90-kDa subunit that does not cross-react with anti-H-beta 3 and anti-H-beta 5 are associated with the alpha v subunit. The structure of the novel 120-kDa subunit found in the embryonic fibroblasts and the 90-kDa subunit found in adult chicken gizzard and the ligand specificities of these novel combinations of alpha v are not known at present, but these integrins are RGD specific. It is hypothesized that embryonic fibroblasts, being the primordial proliferating cells, display a wider spectrum of alpha v-associated beta subunits, whose expression may progressively be restricted or highly reduced in favor of one or more beta subunits in subsequent progenies as differentiation progresses.
整合素是一种异源二聚体细胞表面受体，参与细胞与细胞外基质蛋白的粘附以及细胞间相互作用。通过GRGDSPK-琼脂糖亲和层析分离出RGD肽特异性整合素亚基αv及其相关的β亚基。利用蛋白质印迹法和免疫沉淀技术，与人类系统相比，研究了禽类系统中这种整合素复杂性的本质。正如在人类细胞系统中所发现的那样，在鸡胚成纤维细胞中，整合素αv亚基与90 kDa的β3和110 kDa的β1样亚基相关联，对RGD肽具有高特异性结合。此外，免疫沉淀研究表明，在这些细胞中存在一种未鉴定的120 kDa亚基和一种与αv亚基相关的85 kDaβ5亚基。未观察到与αv相关的β亚基谱在胚胎成纤维细胞培养物的增殖未汇合或非增殖汇合状态方面存在定性差异。在成年鸡肌胃中，一种110 kDa的β1样亚基和一种不与抗H-β3和抗H-β5交叉反应的90 kDa亚基与αv亚基相关联。目前尚不清楚在胚胎成纤维细胞中发现的新型120 kDa亚基和在成年鸡肌胃中发现的90 kDa亚基的结构以及这些αv新组合的配体特异性，但这些整合素是RGD特异性的。据推测，胚胎成纤维细胞作为原始增殖细胞，展示出更广泛的αv相关β亚基谱，随着分化的进行，其表达可能会逐渐受到限制或大幅降低，以利于后续子代中的一种或多种β亚基。
