RGD Reference Report - p32 (gC1qBP) is a general protein kinase C (PKC)-binding protein; interaction and cellular localization of P32-PKC complexes in ray hepatocytes. - Rat Genome Database

RGD Reference Report - p32 (gC1qBP) is a general protein kinase C (PKC)-binding protein; interaction and cellular localization of P32-PKC complexes in ray hepatocytes. - Rat Genome Database

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p32 (gC1qBP) is a general protein kinase C (PKC)-binding protein; interaction and cellular localization of P32-PKC complexes in ray hepatocytes.
Authors:	Robles-Flores, M Rendon-Huerta, E Gonzalez-Aguilar, H Mendoza-Hernandez, G Islas, S Mendoza, V Ponce-Castaneda, MV Gonzalez-Mariscal, L Lopez-Casillas, F
Citation:	Robles-Flores M, etal., J Biol Chem. 2002 Feb 15;277(7):5247-55. Epub 2001 Nov 6.
RGD ID:	1625615
Pubmed:	PMID:11698413 (View Abstract at PubMed)
DOI:	DOI:10.1074/jbc.M109333200 (Journal Full-text)
The aim of this study was to identify cellular proteins that bind protein kinase C (PKC) and may influence its activity and its localization. A 32-kDa PKC-binding protein was purified to homogeneity from the Triton X-100-insoluble fraction obtained from hepatocytes homogenates. The protein was identified by NH(2)-terminal amino acid sequencing as the previously described mature form of p32 (gC1qR). Recombinant p32 was expressed as a glutathione S-transferase fusion protein, affinity-purified, and tested for an in vitro interaction with PKC using an overlay assay approach. All PKC isoforms expressed in rat hepatocytes interacted in vitro with p32, but the binding dependence on PKC activators was different for each one. Whereas PKCdelta only binds to p32 in the presence of PKC activators, PKCzeta and PKCalpha increase their binding when they are in the activated form. Other PKC isoforms such as beta, epsilon, and theta bind equally well to p32 regardless of the presence of PKC activators, and PKCmu binds even better in their absence. It was also found that p32 is not a substrate for any of the PKC isoforms tested, but interestingly, its presence had a stimulatory effect (2-fold for PKCdelta) on PKC activity. We also observed in vivo interaction between PKC and p32 by immunofluorescence and confocal microscopy. A time course of phorbol ester treatment of cultured rat hepatocytes (C9 cells) showed that PKCtheta and p32 are constitutively associated in vivo, whereas PKCdelta activation is required for its association with p32. Our data also showed that phorbol ester treatment induces a transient translocation of p32 from the cytoplasm to the cell nucleus. Together, these findings suggest that p32 may be a regulator of PKC location and function.

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Molecular Function

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Object Symbol	Species	Term	Qualifier	Evidence	With	Notes	Source	Original Reference(s)
Prkcq	Rat	protein binding		IPI	C1qbp (Rattus norvegicus)		RGD
C1qbp	Rat	protein kinase C binding		IDA			RGD

Objects Annotated

Genes (Rattus norvegicus)

C1qbp (complement C1q binding protein)

Prkcq (protein kinase C, theta)

Additional Information