Role of p97 and syntaxin 5 in the assembly of transitional endoplasmic reticulum.
Transitional endoplasmic reticulum (tER) consists of confluent rough and smooth endoplasmic reticulum (ER) domains. In a cell-free incubation system, low-density microsomes (1.17 g cc(-1)) isolated from rat liver homogenates reconstitute tER by Mg(2+)GTP- and Mg(2+)ATP-hydrolysis-dependent membrane fusion. The ATPases associated with different cellular activities protein p97 has been identified as the relevant ATPase. The ATP depletion by hexokinase or treatment with either N-ethylmaleimide or anti-p97 prevented assembly of the smooth ER domain of tER. High-salt washing of low-density microsomes inhibited assembly of the smooth ER domain of tER, whereas the readdition of purified p97 with associated p47 promoted reconstitution. The t-SNARE syntaxin 5 was observed within the smooth ER domain of tER, and antisyntaxin 5 abrogated formation of this same membrane compartment. Thus, p97 and syntaxin 5 regulate assembly of the smooth ER domain of tER and hence one of the earliest membrane differentiated components of the secretory pathway.
Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Québec, Canada.
L
L
Roy
J J
JJ
Bergeron
C
C
Lavoie
R
R
Hendriks
J
J
Gushue
A
A
Fazel
A
A
Pelletier
D J
DJ
Morré
V N
VN
Subramaniam
W
W
Hong
J
J
Paiement
D000251:Adenosine Triphosphatases / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002474:Cell-Free System / Q000378:metabolism; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D018871:Endoplasmic Reticulum, Smooth / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000737:chemistry; D006593:Hexokinase / Q000378:metabolism; D007425:Intracellular Membranes / Q000648:ultrastructure; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008862:Microsomes, Liver / Q000378:metabolism / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D050765:Qa-SNARE Proteins; D051381:Rats
D000906:Antibodies; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009687:Nuclear Proteins; D050765:Qa-SNARE Proteins; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006593:Hexokinase; D000251:Adenosine Triphosphatases; C404942:p97 ATPase; D005033:Ethylmaleimide