Cell Signaling Technology

Product Pathways - Ca / cAMP / Lipid Signaling

Phospho-PKCalpha/beta II (Thr638/641) Antibody #9375

Applications Reactivity MW (kDa) Source
W IP H M Mk (R) 80, 82 Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey
Species enclosed in parentheses are predicted to react based on 100% sequence homology. Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

Phospho-PKC alpha/beta II (Thr638/641) Antibody detects PKC alpha only when phosphorylated at threonine 638 and PKC beta II only when phosphorylated at threonine 641. This antibody also reacts with gamma.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phospho-peptide (KLH-coupled) corresponding to residues surrounding Thr638 of human PKC alpha. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from NIH/3T3 cells, untreated or TPA-treated (0.2 µM), using Phospho-PKCalpha/beta II (Thr638/641) Antibody.

Western Blotting

Western Blotting

Western blot analysis of Baculovirus-expressed PKC isoforms alpha, beta, gamma, delta and epsilon, untreated or treated with lambda protein phosphatase, using Phospho-PKCalpha/beta II (Thr638/641) Antibody (upper) or PKCalpha, beta, gamma, delta, epsilon antibodies (lower).

Sequence

Sequence

Phosphorylation of PKCalpha


Background

Activation of protein kinase C (PKC) is one of the earliest events in a cascade that controls a variety of cellular responses, including secretion, gene expression, proliferation and muscle contraction (1,2). PKC isoforms belong to three groups based on calcium dependency and activators. Classical PKCs are calcium-dependent via their C2 domains and are activated by phosphatidylserine (PS), diacylglycerol (DAG) and phorbol esters (TPA, PMA) through their cysteine-rich C1 domains. Both novel and atypical PKCs are calcium-independent, but only novel PKCs are activated by PS, DAG and phorbol esters (3-5). Members of these three PKC groups contain a pseudo-substrate or autoinhibitory domain that binds to substrate-binding site in the catalytic domain to prevent activation in the absence of cofactors or activators.Control of PKC activity is regulated through three distinct phosphorylation events. Phosphorylation of Thr500 in the activation loop, the autophosphorylation site at Thr641 and at carboxy-terminal hydrophobic site Ser660 occurs in vivo (2). Atypical PKC isoforms lack hydrophobic region phosphorylation, which correlates with the presence of glutamic acid rather than the serine or threonine residues found in more typical PKC isoforms. Either the enzyme PDK1 or a close relative is responsible for PKC activation.A recent addition to the PKC superfamily is PKCμ (PKD), which is regulated by DAG and TPA through its C1 domain. PKD is distinguished by the presence of a PH domain and by its unique substrate recognition and Golgi localization (6). PKC-related kinases (PRK) lack the C1 domain and do not respond to DAG or phorbol esters. Phosphatidylinositol lipids activate PRKs and small Rho-family GTPases bind to the homology region 1 (HR1) to regulate PRK kinase activity (7).

  1. Nishizuka, Y. (1984) Nature 308, 693-698.
  2. Keranen, L.M. et al. (1995) Curr. Biol. 5, 1394-1403.
  3. Mellor, H. and Parker, P.J. (1998) Biochem J. 332 (Pt 2), 281-292.
  4. Ron, D. and Kazanietz, M.G. (1999) FASEB J. 13, 1658-1676.
  5. Moscat, J. and Diaz-Meco, M.T. (2000) EMBO Rep. 1, 399-403.
  6. Baron, C.L. and Malhotra, V. (2002) Science 295, 325-328.
  7. Flynn, P. et al. (2000) J. Biol. Chem. 275, 11064-11070.

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