Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1935753 | Biochemical and Biophysical Research Communications | 2008 | 5 Pages |
Abstract
Pdx-1 is a key regulator of glucose-stimulated insulin gene transcription in β-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 β-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.
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Authors
Françoise Carlotti, Arnaud Zaldumbide, Halima Charif, Eelco J. de Koning, Theo M. Luider, Rob C. Hoeben,