A novel lipid-anchored A-kinase Anchoring Protein facilitates cAMP-responsive membrane events.
Compartmentalization of protein kinases with substrates is a mechanism that may promote specificity of intracellular phosphorylation events. We have cloned a low-molecular weight A-kinase Anchoring Protein, called AKAP18, which targets the cAMP-dependent protein kinase (PKA) to the plasma membrane, and permits functional coupling to the L-type calcium channel. Membrane anchoring is mediated by the first 10 amino acids of AKAP18, and involves residues Gly1, Cys4 and Cys5 which are lipid-modified through myristoylation and dual palmitoylation, respectively. Transient transfection of AKAP18 into HEK-293 cells expressing the cardiac L-type Ca2+ channel promoted a 34 9% increase in cAMP-responsive Ca2+ currents. In contrast, a targeting-deficient mutant of AKAP18 had no effect on Ca2+ currents in response to the application of a cAMP analog. Further studies demonstrate that AKAP18 facilitates GLP-1-mediated insulin secretion in a pancreatic beta cell line (RINm5F), suggesting that membrane anchoring of the kinase participates in physiologically relevant cAMP-responsive events that may involve ion channel activation.
Fraser
I D
ID
Howard Hughes Medical Institute, Oregon Health Sciences University, Portland, OR 97201, USA.
Tavalin
S J
SJ
Lester
L B
LB
Langeberg
L K
LK
Westphal
A M
AM
Dean
R A
RA
Marrion
N V
NV
Scott
J D
JD
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015220:Calcium Channels / Q000502:physiology; D002352:Carrier Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D018076:DNA, Complementary; D004553:Electric Conductivity; D005934:Glucagon / Q000378:metabolism; D052216:Glucagon-Like Peptide 1; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D054758:A Kinase Anchor Proteins; C112596:AKAP7 protein, human; D048868:Adaptor Proteins, Signal Transducing; C487791:Akap7 protein, mouse; D015220:Calcium Channels; D002352:Carrier Proteins; D018076:DNA, Complementary; D007328:Insulin; D008565:Membrane Proteins; D010446:Peptide Fragments; D011498:Protein Precursors; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D000242:Cyclic AMP; D011494:Protein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases