A map of membrane populations isolated from rat exorbital gland

Am J Physiol. 1984 Dec;247(6 Pt 1):G651-61. doi: 10.1152/ajpgi.1984.247.6.G651.

Abstract

We combined separation procedures based on three independent physical properties, sedimentation coefficient, density, and partitioning in an aqueous polymer two-phase system, to generate a three-dimensional subcellular fractionation of rat exorbital lacrimal gland. The distributions of protein and five enzymatic markers define a total of 13 physically and biochemically distinct membrane populations. These include epithelial cell apical membranes, purified 330-fold with respect to the initial homogenate; basal-lateral membranes, purified 80-fold; mitochondria, purified 19-fold; and a major endoplasmic reticulum population, purified 22-fold. Also apparent is a major Golgi population, which is extensively overlapped by other membrane populations; two populations that can be visualized as forming transitions between the endoplasmic reticulum and Golgi membranes; and several populations with unknown subcellular origins. Most of the markers have complex distributions among the isolated membrane populations; this complexity is consistent with current concepts of the synthesis and recycling of membrane constituents and the regulation of cytosolic electrolyte activities.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Membrane / classification
  • Cell Membrane / enzymology
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Centrifugation, Density Gradient
  • Lacrimal Apparatus / ultrastructure*
  • Male
  • Membrane Proteins / metabolism
  • Mitochondria / ultrastructure
  • Rats / anatomy & histology*
  • Rats, Inbred Strains

Substances

  • Membrane Proteins