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I want to jump on the mails related to the question “Help on mouse
anti-P-glycprotein antibody” to ask another question, about the
interference of cytoplasmic proteins and the membrane-P-gp blotting.
Does anyone know if there’re intra-cytoplasmic P-gp(s), either in the
same form than the membrane’s P-gp or other isoforms, or immature P-gp
(higher or lower moleculer weight), or other proteins, structurally
similar to P-gp, which are present in the cytoplasma , and which can
show cross-reactivitywith P-gp’s specific antibodies (C219…).
Thanks for your help!
Makrem BEN REGUIGA
Pharmacokinetics and Clinical Pharmacy Lab.
Faculty of Pharmacy South Paris - Paris XI - France
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The following message was posted to: PharmPK
During post-translational modifications P-gp is
N-glycosylated in the 3rd Transmembrane domain before
membrane encorporation.(MW 180Kda)
In the cytoplasm, a precurssor protein
(MW~120Kda)exists during traficking and prior to
I have observed 2 bands on westerns (~180 Kda and ~120
Kda) in epithelial cells of intestinal, kidney and
liver origin with C219 and F4 antibodies. The 120 Kda
band disappears on boiling the samples for >10 min.
Even MDCK-MDR1 cells overexpressing P-gp show presence
of both bands.
There are reports that even the nuclear membrane has
P-gp. I am not aware of the MW though.
Hope this helps.
College of Pharmacy
Department of Pharmaceutical Sciences ( Biopharmaceutics)
University of Cincinnati Medical center
3223, Eden Avenue
Cincinnati , OH 45267-004
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