Properties of a GTP sensitive microdomain in rough microsomes.
Biochim Biophys Acta
; 898(1): 6-22, 1987 Mar 26.
Article
em En
| MEDLINE
| ID: mdl-3828332
ABSTRACT
Stripped rough microsomes (SRM) fuse when incubated with physiological concentrations of GTP and MgCl2. In order to examine further to what extent such fusions are associated with other membrane functions of rough endoplasmic reticulum, we have evaluated the role of cytosolically exposed peptide constituents of SRM in fusion, and the possible relationship of GTP/MgCl2-induced fusion in protein transport across endoplasmic reticulum (ER) membranes, and in ER-Golgi interactions. Controlled proteolytic digestion of SRM led to the loss of fusion capability at 15 micrograms/ml trypsin--a concentration which maintained the latency of intraluminal mannose-6-phosphatase. Hence, a cytosolically exposed protein(s) regulated fusion. Based on ribonuclease-induced ribosome capping experiments, it was further concluded that the cytosolic oriented protein(s) was sequestered beneath the ribosome. As co-translational cell free translocation of placental lactogen across SRM was similar in control membranes compared to those rendered incapable of fusing, it was concluded that the fusion phenomenon may not be related to translocation. Under conditions promoting homologous fusion of SRM or Golgi membranes, mixtures of the two membranes showed no heterologous membrane fusion as assessed morphologically or by the transport of newly synthesized membrane glycoprotein. These experiments attest to the specificity of cytosolically exposed protein(s) in regulating nucleotide/divalent cation-induced membrane fusion.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Microssomos Hepáticos
/
Guanosina Trifosfato
/
Membranas Intracelulares
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1987
Tipo de documento:
Article