Human calcium-calmodulin dependent protein kinase I: cDNA cloning, domain structure and activation by phosphorylation at threonine-177 by calcium-calmodulin dependent protein kinase I kinase.

Abstract

Human Ca(2+)‐calmodulin (CaM) dependent protein kinase I (CaMKI) encodes a 370 amino acid protein with a calculated M(r) of 41,337. The 1.5 kb CaMKI mRNA is expressed in many different human tissues and is the product of a single gene located on human chromosome 3. CaMKI 1–306, was unable to bind Ca(2+)‐CaM and was completely inactive thereby defining an essential component of the CaM‐binding domain to residues C‐terminal to 306. CaMKI 1–294 did not bind CaM but was fully active in the absence of Ca(2+)‐CaM, indicating that residues 295–306 are sufficient to maintain CaMKI in an auto‐inhibited state. CaMKI was phosphorylated on Thr177 and its activity enhanced approximately 25‐fold by CaMKI kinase in a Ca(2+)‐CaM dependent manner. Replacement of Thr177 with Ala or Asp prevented both phosphorylation and activation by CaMKI kinase and the latter replacement also led to partial activation in the absence of CaMKI kinase. Whereas CaMKI 1–306 was unresponsive to CaMKI kinase, the 1–294 mutant was phosphorylated and activated by CaMKI kinase in both the presence and absence of Ca(2+)‐CaM although at a faster rate in its presence. These results indicate that the auto‐inhibitory domain in CaMKI gates, in a Ca(2+)‐CaM dependent fashion, accessibility of both substrates to the substrate binding cleft and CaMKI kinase to Thr177. Additionally, CaMKI kinase responds directly to Ca(2+)‐CaM with increased activity.

Cloning of a Calmodulin Kinase I Homologue fromSchizosaccharomyces pombe

“…From the expression library screen, we obtained a number of clones, of which one was found to encode the S. pombe homologue of CaMK-I, the gene that we have named cmk1. The gene encodes a protein kinase with a predicted molecular mass of 39 kDa and that is 40% identical at the primary amino acid sequence level to rat and human CaMK-I (11,31). In addition, it was possible to obtain a partial genomic clone through PCR amplification of cmk1 sequences from S. pombe genomic DNA.…”

Activation of the myocyte enhancer factor-2 transcription factor by calcium/calmodulin-dependent protein kinase-stimulated binding of 14-3-3 to histone deacetylase 5

“…Expression plasmids for FLAG-tagged HDAC1 (pBJ) and HDAC3 (pcDNA6) have been described (5). The cDNA for CaMKI encodes a truncated protein that is constitutively active (19).…”

Ca2+-independent Activation of Ca2+/Calmodulin-dependent Protein Kinase II Bound to the C-terminal Domain of CaV2.1 Calcium Channels

“…Ca v 2.1 channels form a presynaptic complex that is co-localized with nearly 100 interacting proteins at the active zone, which serves to dock neurotransmitter vesicles, modulate Ca v 2.1 channel function, and mediate exocytosis (9,10). Ca 2ϩ /CaM-dependent protein kinase II (CaMKII) is a ubiquitous, multifunctional serine/threonine kinase (11)(12)(13)(14). It mediates Ca 2ϩ -dependent phosphorylation of a wide range of neuronal targets (15,16).…”