Interaction of rat hormone-sensitive lipase with adipocyte lipid-binding protein

Hormone-sensitive lipase (HSL) is a cytosolic neutral lipase that functions as the rate-limiting enzyme for the mobilization of free fatty acids in ad ipose tissue. By using the yeast two-hybrid system to examine the potential interaction of HSL with other cellular proteins, evidence is provided to d emonstrate a direct interaction of RSL with adipocyte lipid-binding protein (ALBP), a member of the family of intracellular lipid-binding proteins tha t binds fatty acids, retinoids, and other hydrophobic ligands, The interact ion was demonstrated in vitro by the binding of ALBP to HSL translated in v itro, to HSL in extracts of HSL overexpressing Chinese hamster ovary (CHO) cells, and to HSL in extracts of rat adipose tissue. Finally, the presence of ALBP was documented in immune complexes from rat adipose tissue immunopr ecipitated with anti-HSL antibodies. The HSL-ALBP interaction was mapped to an N-terminal 300-aa region of HSL that is distinct from the C-terminal ca talytic domain. These results suggest that HSL-derived fatty acids are boun d by ALBP to facilitate intracellular trafficking of hydrophobic lipids.