Calcium/calmodulin-dependent protein kinase kinase: identification of regulatory domains.
Biochemistry
; 36(42): 12823-7, 1997 Oct 21.
Article
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| MEDLINE
| ID: mdl-9335539
We recently cloned a calmodulin-dependent protein kinase kinase (CaM-KK) which phosphorylates and activates CaM-KI and CaM-KIV [Tokumitsu, H., Enslen, H., and Soderling, T. R. (1995) J. Biol. Chem. 270, 19320-19324]. In the present study, we have identified its regulatory CaM-binding and autoinhibitory domains (CBD and AID, respectively) using a series of COOH-terminal truncations and site-directed mutants expressed in COS-7 cells. Truncation mutant CaM-KK1-463 activated CaM-KIV and bound CaM similar to wild-type enzyme (CaM-KK1-505); CaM-KK1-448 did not bind CaM and was largely inactive; and CaM-KK1-434 also did not bind CaM but activated a CaM-independent mutant of CaM-KIV in the absence of Ca2+/CaM. Substitution of triple negative charges (Asp) at positions 455RKR, 448ILV, or 443SWT blocked CaM binding and suppressed by 70-90% CaM-KK activities. Mutants 438VKL and 435KNS to DDD exhibited partial Ca2+/CaM-independent activities. These results identify overlapping AID and CBD between residues 430 and 460 in CaM-KK, similar to other CaM-Ks. Consistent with this assignment, the synthetic peptide corresponding to residues 438-463 bound CaM in a Ca2+-dependent manner with a Kd in the low nanomolar range. Furthermore, phosphorylation by cAMP-kinase of Ser458 at the COOH-terminus of the CBD in CaM-KK, which suppresses subsequent CaM binding [Wayman, G., Tokumitsu, H., and Soderling, T. R. (1997) J. Biol. Chem. 272, 16073-16076], was blocked by prior binding of Ca2+/CaM to CaM-KK.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Quinasas
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
Idioma:
En
Revista:
Biochemistry
Año:
1997
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos