Morphology of proteoliposomes reconstituted with purified lac carrier protein from Escherichia coli.

Published

Journal Article

Proteoliposomes reconstituted with purified lac carrier protein from Escherichia coli were ultra-rapidly frozen and examined by freeze-fracture-etch electron microscopy. The proteoliposomes are greater than 95% unilamellar, and the majority are 30-150 nm in diameter. Fracture faces of proteoliposomes (at a protein:lipid molecular ratio of about 1:2500) display 7.0-nm diameter globular intramembrane particles uniformly distributed on convex and concave surfaces. Calculations of particle composition suggest that each intramembrane particle probably contains one or two molecules of the 46.5-kDa transmembranous lac carrier protein, depending on the correction factor for the thickness of the metal deposited to form the platinum/carbon replicas. Etched surfaces of the proteoliposomes are smooth. Incubation of the proteoliposomes with monoclonal antibody 4B1, which binds to an epitope in the lac carrier on the exterior of the proteoliposomes, dramatically alters the intramembrane particle distribution. After incubation with antibody, the convex (inner monolayer) fracture faces are nearly devoid of intramembrane particles, and an overall 4-fold reduction in the total number of intramembrane particles is observed.

Full Text

Duke Authors

Cited Authors

  • Costello, MJ; Viitanen, P; Carrasco, N; Foster, DL; Kaback, HR

Published Date

  • December 1984

Published In

Volume / Issue

  • 259 / 24

Start / End Page

  • 15579 - 15586

PubMed ID

  • 6392300

Pubmed Central ID

  • 6392300

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng