Selective solubilization of two populations of polypeptides from bovine retinal basement membranes

Academic Article

Abstract

  • Basement membranes isolated from the entire neural retinae of normal cows consist of a heterogeneous mixture of polypeptides resolvable as two major populations, one collagenous and the other non-collagenous. The non-collagenous population consists of disulfide-bonded aggregates of which the major fraction is soluble in lithium dodecyl sulfate (LDS) at 4°C without reducing agent, with the remainder requiring reduction for solubilization at 4°C. Only the second 4°C extract is contaminated with small amounts of hydroxylated amino acids. The non-collagenous population consists of up to 25 polypeptides detectable in sodium dodecyl sulfate (SDS) gels, all of which stain blue with Coomassie Blue R-250, are insensitive to bacterial collagenase and migrate on or slightly below the central diagonal in urea- SDS SDS electrophoresis. The collagenous population is soluble in LDS at 100°C under reducing conditions and has a collagenous amino acid composition, although consisting of only 272 glycine residues/1000. This fraction consists of four major and four minor polypeptides detectable in SDS gels, all of which stain red (metachromatically) with Coomassie Blue R-250, are degraded by bacterial collagenase and migrate below the central diagonal in urea- SDS SDS electrophoresis. The four major collagenous polypeptides are larger than the α-chains of type I collagen. In total, the solubilized proteins account for 60% of the general protein, but only 30% of the sum of hydroxyproline and hydroxylysine. The insoluble residue has a collagenous amino acid composition similar to that of the 100°C extract, but with lower 3-hydroxyproline and hydroxylysine contents. © 1983.
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    Author List

  • Duhamel RC; Meezan E; Brendel K
  • Start Page

  • 257
  • End Page

  • 267
  • Volume

  • 36
  • Issue

  • 2