Sterol carrier protein-2 suppresses microsomal acyl-CoA hydrolysis.
Although sterol carrier protein 2 (SCP-2) has long been regarded primarily as a sterol transfer protein, its actual physiological function is not known. The recent discovery that SCP-2 binds long chain fatty acyl-CoAs (LCFA-CoAs) with high affinity suggests additional roles for SCP-2 in cellular utilization of LCFA-CoAs for synthesis of glycerides and cholesterol esters. Concomitant to these anabolic pathways, LCFA-CoAs are also degraded by cellular hydrolases. The purpose of the work presented herein was to determine if SCP-2 altered the aqueous pool of LCFA-CoA by (i) extracting LCFA-CoA from microsomal membranes, and (ii) protecting LCFA-CoA from microsomal hydrolase activity. The data demonstrated for the first time that SCP-2 increases the aqueous pool of oleoyl-CoA by increasing the aqueous/membrane distribution oleoyl-CoA by 2.4-fold. In addition, SCP-2 inhibited the hydrolysis of oleoyl-CoA by microsomal acyl-CoA hydrolase 1.6-2.4 fold, depending on the concentration of oleoyl-CoA. By simultaneously extracting LCFA-CoA from membranes and inhibiting LCFA-CoA degradation SCP-2 may potentiate LCFA-CoA transacylation and modulate the role of LCFA-CoAs as intracellular signaling molecules.
Jolly
C A
CA
Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station 77843-4466, USA.
Chao
H
H
Kier
A B
AB
Billheimer
J T
JT
Schroeder
F
F
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010940:Plant Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism
D000214:Acyl Coenzyme A; D002352:Carrier Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; C072087:sterol carrier proteins; C017585:oleoyl-coenzyme A