The splice variants of D-AKAP1 differ in subcellular localization and tissue-specific expression

Unlike other known A-Kinase anchoring proteins (AKAPs) which tether the type II regulatory subunit of cAMP-dependent protein kinase. I)-AKAP1 can bind both the type I and the type II regulatory subunit, cl)NA cloning of I)-AKAPI revealed that in addition to the 526 amino acid core. there are two N-terminal splices, and two C-terminal splice. To determine the expression pattern of these different splice variants, a multiple tissue Northern blot was probed with splice-specific cDNA probes. The NI splice was specifically expressed in liver, and the C1 splice was predominantly expressed in testis. The C2 splice had a wide tissue distribution similar to the overall expression pab tern. "Using microinjection techniques, the NO splice of D-AKAP1 was found to target to the mitochondria, while the N1 splice primarily localized to the endoptasmic reticulum. The co-expression of the D-AKAPla isoform, which employs the NO splice, and RIIb in mitochondria-rich brown adipose tissues and their interaction in vitro indicated that such interaction could be physiologically important.