title: A small novel A-kinase anchoring protein (AKAP) that localizes specifically protein kinase A-regulatory subunit I (PKA-RI) to the plasma membrane.
abstract: Protein kinase A-anchoring proteins (AKAPs) provide spatio-temporal specificity for the omnipotent cAMP-dependent protein kinase (PKA) via high affinity interactions with PKA regulatory subunits (PKA-RI, RII). Many PKA-RII-AKAP complexes are heavily tethered to cellular substructures, whereas PKA-RI-AKAP complexes have remained largely undiscovered. Here, using a cAMP affinity-based chemical proteomics strategy in human heart and platelets, we uncovered a novel, ubiquitously expressed AKAP, termed small membrane (sm)AKAP due to its specific localization at the plasma membrane via potential myristoylation/palmitoylation anchors. In vitro binding studies revealed specificity of smAKAP for PKA-RI (K(d) = 7 nM) over PKA-RII (K(d) = 53 nM) subunits, co-expression of smAKAP with the four PKA R subunits revealed an even more exclusive specificity of smAKAP for PKA-RIα/β in the cellular context. Applying the singlet oxygen-generating electron microscopy probe miniSOG indicated that smAKAP is tethered to the plasma membrane and is particularly dense at cell-cell junctions and within filopodia. Our preliminary functional characterization of smAKAP provides evidence that, like PKA-RII, PKA-RI can be tightly tethered by a novel repertoire of AKAPs, providing a new perspective on spatio-temporal control of cAMP signaling.
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
authors.forename: Pepijn P
authors.initials: PP
authors.lastname: Burgers
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Ma
authors.forename: Luigi
authors.initials: L
authors.lastname: Margarucci
authors.forename: Mason
authors.initials: M
authors.lastname: Mackey
authors.forename: Marcel A G
authors.initials: MA
authors.lastname: van der Heyden
authors.forename: Mark
authors.initials: M
authors.lastname: Ellisman
authors.forename: Arjen
authors.initials: A
authors.lastname: Scholten
authors.forename: Susan S
authors.initials: SS
authors.lastname: Taylor
authors.forename: Albert J R
authors.initials: AJ
authors.lastname: Heck
mesh_terms: D054758:A Kinase Anchor Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism*; D054743:Cyclic AMP-Dependent Protein Kinase Type I / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D007365:Intercellular Junctions / Q000235:genetics / Q000378:metabolism; D054878:Lipoylation / Q000502:physiology*; D008297:Male; D051379:Mice; D011485:Protein Binding; D011554:Pseudopodia / Q000235:genetics / Q000378:metabolism; D015290:Second Messenger Systems / Q000502:physiology*
chemical_list: D054758:A Kinase Anchor Proteins; D000242:Cyclic AMP; D054743:Cyclic AMP-Dependent Protein Kinase Type I