NH2-terminal targeting motifs direct dual specificity A-kinase- anchoring protein 1 (D-AKAP1) to either mitochondria or endoplasmic reticulum

Lily Jun Shen Huang, Lin Wang, Yuliang Ma, Kyle Durick, Guy Perkins, Thomas J. Deerinck, Mark H. Ellisman, Susan S. Taylor

Research output: Contribution to journalArticle

132 Scopus citations

Abstract

Subcellular localization directed by specific targeting motifs is an emerging theme for regulating signal transduction pathways. For cAMP- dependent protein kinase (PKA), this is achieved primarily by its association with A-kinase-anchoring proteins (AKAPs). Dual specificity AKAP1, (D-AKAP1) binds to both type I and type II regulatory subunits and has two NH2- terminal (NO and N1) and two COOH-terminal (C1 and C2) splice variants (Huang et al., 1997. J. Biol. Chem. 272:8057). Here we report that the splice variants of D-AKAP1 are expressed in a tissue-specific manner with the NH2- terminal motifs serving as switches to localize D-AKAP1 at different sites. Northern blots showed that the N1 splice is expressed primarily in liver, while the C1 splice is predominant in testis. The C2 splice shows a general expression pattern. Microinjecting expression constructs of D-AKAP1(N0) epitope-tagged at either the NH2 or the COOH terminus showed their localization to the mitochondria based on immunocytochemistry. Deletion of N0(1-30) abolished mitochondrial targeting while N0(1-30)-GFP localized to mitochondria. Residues 1-30 of NO are therefore necessary and sufficient for mitochondria targeting. Addition of the 33 residues of N1 targets D-AKAP1 to the ER and residues 1-63 fused to GFP are necessary and sufficient for ER targeting. Residues 14-33 of N1 are especially important for targeting to ER; however, residues 1-33 alone fused to GFP gave a diffuse distribution. N1(14- 33) thus serves two functions: (a) it suppresses the mitochondrial-targeting motif located within residues 1-30 of NO and (b) it exposes an ER-targeting motif that is at least partially contained within the N0(1-30) motif. This represents the first example of a differentially targeted AKAP and adds an additional level of complexity to the PKA signaling network.

Original languageEnglish (US)
Pages (from-to)951-959
Number of pages9
JournalJournal of Cell Biology
Volume145
Issue number5
DOIs
StatePublished - May 31 1999

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Keywords

  • AKAP
  • Endoplasmic reticulum
  • Mitochondria
  • Subcellular localization
  • cAMP-dependent protein kinase

ASJC Scopus subject areas

  • Cell Biology

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