The 45-kDa form of Pdx-1 does not result from post-translational modifications

F Carlotti, A Zaldumbide, Halima Charif, EJ Koning, Theo Luider, RC Hoeben

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Abstract

Pdx-1 is a key regulator of glucose-stimulated insulin gene transcription in beta-cells. The regulation of Pdx-1 in response to glucose has previously been associated with a remarkable shift in electrophoretic mobility on SDS-PAGE from 31 to 45 kDa. This has been attributed to different post-translational modifications including phosphorylation, sumoylation or glycosylation. However, and in contrast with previous studies, we describe in this paper that Pdx-1 produced in Escherichia coli, by in vitro transcription/translation or exogenously expressed in eukaryotic cells, migrates with an apparent molecular mass of 45 kDa despite a calculated mass of 31 kDa. Moreover, we show that the migration of endogenous Pdx-1 obtained from a mouse beta-cell line as well as from human primary islets is not dependent on glucose concentration. Taken together, these data, validated by mass spectrometry techniques, establish that anomalous migration of Pdx-1 on SDS-PAGE does not result from post-translational modifications. (C) 2008 Elsevier Inc. All rights reserved.
Original languageUndefined/Unknown
Pages (from-to)225-229
Number of pages5
JournalBiochemical & Biophysical Research Communications
Volume370
Issue number2
DOIs
Publication statusPublished - 2008

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