Differential solubility of subcomponents of rat glomerular basement membrane

Marked differences were found in the electrophoretic profiles and amino-acid compositions of components prepared from rat glomerular basement membrane (GBM) by a number of different solubilization procedures. Treatment with reducing agent resulted in a simplified electrophoretic pattern which was characterized by the presence of a major collagenous component with a mol.wt. of 150 000. In contrast, detergent solubilized mainly lower-mol.-wt. material which had a more polar amino-acid composition. When both reagents were used together the majority of the basement-membrane material was solubilized within 2 h and components with mol.wts. of 170 000 and 135 000 were predominant in the pro-alpha region of the gel. Treatment for a further 16 h was required to solubilize higher-mol.-wt. material and to achieve maximum solubility of components in the pro-alpha region with mol.wts. of 185 000 and 150 000. These methods provide a means of separating subcomponents of rat GBM while avoiding the problems of degradation inherent in enzymatic procedures.