Adipose differentiation related protein (ADRP) expressed in transfected COS-7 cells selectively stimulates long chain fatty acid uptake

Adipose differentiation related protein (ADRP) is a 50-kDa novel protein cl oned from a mouse 1246 adipocyte cDNA library, rapidly induced during adipo cyte differentiation. We have examined ADRP function, and we show here that ADRP facilitates fatty acid uptake in COS cells transfected with ADRP cDNA We demonstrate that uptake of long chain fatty acids was significantly sti mulated in a time-dependent fashion in ADRP-expressing COS-7 cells compared with empty vector-transfected control cells. Oleic acid uptake velocity in creased significantly in a dose-dependent manner in ADRP-expressing COS-7 c ells compared with control cells. The transport K-m was 0.051 mu M, and V-m ax was 57.97 pmol/10(5) cells/min in ADRP-expressing cells, and K-m was 0.0 93 mu M and V-max was 20.13 pmol/10(5) cells/min in control cells. The olea te uptake measured at 4 degrees C was only 10% that at 37 degrees C, ADRP a lso stimulated uptake of palmitate and arachidonate but had no effect on up take of medium chain fatty acid such as octanoic acid and glucose. These da ta suggest that ADRP specifically enhances uptake of long chain fatty acids by increasing the initial rate of uptake and provide novel information abo ut ADRP function as a saturable transport component for long chain fatty ac ids.