Product Pathways - Ca / cAMP / Lipid Signaling
PKA C-β Kinase #7688
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Description
Purified recombinant full length human PKAC-beta (Met1-Phe351) kinase, supplied as a GST fusion protein.
Source / Purification
The GST-Kinase fusion protein was produced using a baculovirus expression system with a construct expressing human PKA C-beta (Met1-Phe351) (GenBank Accession No. NM_002731) with an amino-terminal GST tag. The protein was purified by one-step affinity chromatography using glutathione-agarose.
Gel Staining
Figure 1. The purity of the GST-PKA C-beta fusion protein was analyzed using SDS/PAGE followed by Coomassie stain.
Kinase Assay - Radiometric
Figure 2. PKA C-beta kinase activity was measured in a radiometric assay using the following reaction conditions: 4 mM MOPS, pH 7.2, 2.5 mM β-glycerophosphate, 1 mM EGTA, 0.4 mM EDTA, 4 mM MgCl2, 0.05 mM DTT, 40 ng/μL BSA, 50 μM ATP, Substrate: CREBtide 400 ng/μL and recombinant PKA C-beta: variable.
Quality Control
The theoretical molecular weight of the GST-PKAC-beta fusion protein is 66 kDa. The purified kinase was quality controlled for purity using SDS-PAGE followed by Coomassie stain [Fig.1]. PKAC-beta kinase activity was determined using a radiometric assay [Fig.2].
Background
The second messenger cyclic AMP (cAMP) activates cAMP-dependent protein kinase (PKA or cAPK) in mammalian cells and controls many cellular mechanisms such as gene transcription, ion transport and protein phosphorylation (1). Inactive PKA is a heterotetramer composed of a regulatory subunit (R) dimer and a catalytic subunit (C) dimer, and in this inactive state, the pseudosubstrate sequences on the R subunits block the active sites on the C subunits. Three C subunit isoforms (C-α, C-β and C-γ) and two families of regulatory subunits (RI and RII) with distinct cAMP binding properties have been identified. Within the two R families, two isoforms, α and β (RI-α, RI-β, RII-α and RII-β) exist. Upon binding of cAMP to the R subunits, the autoinhibitory contact is eased and active monomeric C subunits are released. PKA shares substrate specificity with Akt (PKB) and PKC, which is characterized by an arginine at position -3 relative to the phosphorylated serine or threonine residue (2). Substrates that present this consensus sequence and have been shown to be phosphorylated by PKA are Bad (Ser155), CREB (Ser133) and GSK-3 (GSK-3α Ser21 and GSK-3β Ser9) (3-5). In addition, combined knock-down of PKA C-α and C-β blocks cAMP-mediated phosphorylation of Raf (Ser43 and Ser259) (6). Autophosphorylation and phosphorylation by PDK-1 are two known mechanisms responsible for phosphorylation of the C subunit at Thr197 (7).
- Montminy, M. (1997) Annu. Rev. Biochem. 66, 807-822.
- Dell'Acqua, M.L. and Scott, J.D. (1997) J. Biol. Chem. 272, 12881-12884.
- Tan, Y. et al. (2000) J. Biol. Chem. 275, 25865-25869.
- Gonzalez, G.A. and Montminy, M.R. (1989) Cell 59, 675-680.
- Fang, X. et al. (2000) Proc. Natl. Acad. Sci. USA 97, 11960-11965.
- Dumaz, N. and Marais, R. (2003) J. Biol. Chem. 278, 29819 -29823.
- Moore, M.J. et al. (2002) J. Biol. Chem. 277, 47878-47884.
Application References
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Companion Products
This product is for in vitro research use only and is not intended for use in humans or animals. This product is not intended for use as therapeutic or in diagnostic procedures.
