Type II regulatory subunit dimerization determines the subcellular localization of the cAMP-dependent protein kinase.
The type II cAMP-dependent protein kinase (PKA) is localized to specific subcellular environments through binding of dimeric regulatory subunits (RII) to anchoring proteins. Cytoskeletal localization occurs through RII dimer interaction with the PKA substrate molecule microtubule-associated protein 2 (MAP2). RII alpha deletion mutants and RII alpha/endonexin chimeras retained MAP2 binding activity if they contained the first 79 residues of the molecule. Disruption of RII alpha dimerization always prevented MAP2 interaction because 1) RII delta 1-14 (an amino-terminal deletion mutant lacking residues 1-14) was unable to bind MAP2 or form dimers, and 2) a modified RII alpha monomer including residues 1-14 did not bind MAP2. Chimeric proteins containing the first 30 residues of RII alpha fused to endonexin II formed dimers but did not bind MAP2. This suggested other side-chains between residues 30-79 also participate in MAP2 interaction. Peptide studies indicate additional contact with MAP2 may occur through an acidic region (residues 68-82) close to the RII autoinhibitor domain. Therefore, anchored PKA holoenzyme topology may position the catalytic subunit and MAP2 as to allow its preferential phosphorylation upon kinase activation.
Scott
J D
JD
Vollum Institute for Advanced Biomedical Research, Portland, Oregon 97201.
Stofko
R E
RE
McDonald
J R
JR
Comer
J D
JD
Vitalis
E A
EA
Mangili
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D017304:Annexin A5; D002135:Calcium-Binding Proteins / Q000235:genetics; D002417:Cattle; D002451:Cell Compartmentation; D003599:Cytoskeleton / Q000201:enzymology; D004252:DNA Mutational Analysis; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D015183:Restriction Mapping; D013329:Structure-Activity Relationship
D017304:Annexin A5; D002135:Calcium-Binding Proteins; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; D010446:Peptide Fragments; D011494:Protein Kinases