Site specific deacylation by ABHD17a controls BK channel splice variant activity

S-acylation, the reversible post-translational lipid modification of proteins is an important mechanism to control the properties and function of ion channels and other polytopic transmembrane proteins. However, while increasing evidence reveals the role of diverse acyl protein transferases (zDHHC) in controlling ion channel S-acylation the acyl protein thioesterases that control ion channel deacylation are very poorly defined. Here we show that the α/β-hydrolase domain-containing protein 17a (ABHD17a) deacylates the STREX domain of large conductance voltage- and calcium- activated potassium (BK) channels inhibiting channel activity independently of effects on channel surface expression. Importantly, ABHD17a deacylates BK channels in a site- specific manner as it has no effect on the S-acylated S0-S1 domain conserved in all BK channels that controls membrane trafficking and is deacylated by the acyl protein thioesterase Lypla1.  Thus, distinct S-acylated domains in the same polytopic transmembrane protein can be regulated by different acyl protein thioesterases revealing mechanisms for generating both specificity and diversity for these important enzymes to control the properties and functions of ion channels.