Study on the porcine tubular basement membrane

Porcine kidney slices were gently homogenized with 0.9% NaCl in a Waring blender, followed by sieving of the homogenate to isolate tubules. The tubular basement membrane (TBM) was then prepared from the tubules by sonication in 1.0 M NaCl. Electron micrographs indicated a high degree of purity of the TBM with negligible contamination of fibrillar collagen. Analytical data showed that the TBM was a glycoprotein containing approximately 10% of carbohydrates. Of the sugar components, glucose and galactose comprised approximately 70% of the total carbohydrates and glycosylgalactosylhydroxylysine was detected in an alkaline hydrolyzate of the TBM. Besides them, mannose, fucose, glucosamine, galactosamine and sialic acid were also detected. The protein portion of the TBM contained hydroxyproline, hydroxylysine, half cystine, methionine and a large amount of glycine as the characteristic amino acids. Polyacrylamide gel-electrophoresis of the TBM gave 15 bands.