Regulation of intrasteric inhibition of the multifunctional calcium/calmodulin-dependent protein kinase.
A regulatory region involved in both autoinhibition and calmodulin (CaM) binding has previously been identified in the multifunctional Ca2+/CaM-dependent protein kinase (CaM kinase II). We have tested the role of various segments of the regulatory region in autoinhibition by the analysis of a series of truncation, substitution, and deletion mutants of the CaM kinase II alpha subunit (CaM kinase II alpha). Unexpectedly, the sequence Lys-Lys-Phe-Asn at positions 291-294, adjacent to the CaM binding domain, was found to be sufficient to maintain an inhibited state in a truncated form of the kinase. However, these residues are not essential in the context of the full-length protein, indicating the importance of additional residues from the overlapping CaM binding domain. We propose here a molecular model for CaM kinase II alpha based on the three-dimensional structure of the cAPK-PKI-(5-24) (protein kinase inhibitor fragment) complex. It is predicted from this model that autoinhibition is of the pseudosubstrate variety and that autophosphorylation of Thr-286 could occur by an intersubunit reaction in the holoenzyme complex.
Cruzalegui
F H
FH
Department of Pharmacology, Duke University Medical Center, Durham, NC 27710.
Kapiloff
M S
MS
Morfin
J P
JP
Kemp
B E
BE
Rosenfeld
M G
MG
Means
A R
AR
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D003198:Computer Simulation; D004252:DNA Mutational Analysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
D002148:Calmodulin-Binding Proteins; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases