Do adult rat ventricular myocytes express protein kinase
c[alpha]?.
Rybin, Vitalyi, and Susan F. Steinberg.
Departments of Medicine and Pharmacology, Columbia University, New
York, New York 10032
APStracts 3:0473H, 1996.
While calcium-insensitive PKC isoforms (PKC and PKC[delta]) are
consistently detected in adult ventricular myocytes, the evidence
that adult ventricular myocytes also express calcium-sensitive
PKC[alpha] is inconsistent. The current study used four different
anti-PKC[alpha] antibodies to resolve some of the uncertainties
regarding the immunodetection of PKC[alpha] in adult ventricular
myocytes. Three of the antibodies used in this study barely (Gibco
-BRL) or rather faintly (Transduction Laboratories, and Seikagaku
America, Inc.) recognize PKC[alpha] in crude preparations from adult
ventricular myocytes. While each of these antibodies recognize a
prominent 80-kDa-band which is similar in size to PKC[alpha], this
represents nonspecific immunoreactivity and should not be confused
with PKC[alpha]. This conclusion is based upon peptide blocking
experiments (Gibco-BRL), the absence of the requisite sensitivity to
calcium- and PMA-induced translocation (Seikagaku America, Inc. and
Transduction Laboratories) and/or the failure to co-purify with
PKC[alpha] on DEAE-Sephacel chromatography. Nevertheless, an antibody
from Upstate Biotechnology Inc. clearly recognizes PKC[alpha], and
not other unrelated non-specific immunoreactive species, in crude
preparations from adult ventricular myocytes. Each of the antisera
used in this study could detect PKC[alpha] immunoreactivity following
chromatographic purification of the samples to enrich for PKC[alpha]
and remove non-specific immunoreactive proteins. These results
suggest that PKC[alpha] is expressed by adult ventricular myocytes
and argue that differences in the sensitivity and/or specificity of
available antisera contribute to at least some of the confusion
regarding PKC[alpha] expression in adult ventricular myocytes.
Received 2 May 1996; accepted in final form 16 October 1996.
APS Manuscript Number H392-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996