Heterogeneous fatty acylation of Src family kinases with polyunsaturated fatty acids regulates raft localization and signal transduction

Fatty acylation of Src family kinases is essential for localization of the modified proteins to the plasma membrane and to plasma membrane rafts. It h as been suggested that the presence of saturated fatty acyl chains on prote ins is conducive for their insertion into liquid ordered lipid domains pres ent in rafts. The ability of unsaturated dietary fatty acids to be attached to Src family kinases has not been investigated. Here we demonstrate that heterogeneous fatty acylation of Src family kinases occurs and that the nat ure of the attached fatty acid influences raft-mediated signal transduction . By using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we show that in addition to 14:0 (myristate), 14:1 and 14:2 f atty acids can be attached to the N-terminal glycine of the Src family kina se Fyn when the growth media are supplemented with these dietary fatty acid s. Moreover, we synthesized novel iodinated analogs of oleate and stearate, and we showed that heterogeneous S-acylation can occur on cysteine residue s within Fyn as well as G alpha, GAP43, and Ras. Modification of Fyn with u nsaturated or polyunsaturated fatty acids reduced its raft localization and resulted in decreased T cell signal transduction. These studies establish that heterogeneous fatty acylation is a widespread occurrence that serves t o regulate signal transduction by membrane-bound proteins.