Abstract
It has been proposed that the amino-terminal domain of ADP-ribosylation factor (ARF) is critical for its stimulation of cholera toxin ADP-ribosyltransferase activity. In this study, recombinant ARF1 (rARF1), r delta 13ARF1 (recombinant ARF1 lacking the first 13 amino acids) and rPKA14ARF1 (recombinant ARF1 in which the first 14 amino acids were replaced by the first 7 amino acids of the cAMP-dependent protein kinase catalytic subunit) were used to assess the effect of the amino terminus on the ability of ARF to enhance ADP-ribosylation of agmatine by the cholera toxin A subunit. The GTP-dependent ARF activities of r delta 13ARF1 and rPKA14ARF1 were similar to that of rARF1, whereas the GTP requirement for half-maximal activation of cholera toxin A, was somewhat higher for rARF1 than it was for r delta 13ARF1 and rPKA14ARF1. These results are consistent with the view that the amino terminus of ARF1 is not critical for its action as a GTP-dependent activator of cholera toxin.
Highlights
It has been proposed that the amino-terminal domainas stimulation of cholera toxin ADP-ribosyltransferase activity, of ADP-ribosylation factor (ARFi)s critical for its stimu- has been detected in a wide variety of tissues, using as sublation of cholera toxin ADP-ribosyltransferase activity. strates agmatine or G, purified from rabbit liver [1, 2].Cyto
A peptide withthe amino acid sequenceof the amino terminus of ARF1, devoid of ADP-ribosylation factors (ARFs)-like activity, inhibited ARF
What higher for rARFl than it was for rAl3ARF1 and functions, including its ability to enhance endosome fusion and rPKA14ARFl
Summary
It has been proposed that the amino-terminal domainas stimulation of cholera toxin ADP-ribosyltransferase activity, of ADP-ribosylation factor (ARFi)s critical for its stimu- has been detected in a wide variety of tissues, using as sublation of cholera toxin ADP-ribosyltransferase activity. strates agmatine or G,, purified from rabbit liver [1, 2].Cyto-. That sequence differthat the amino terminus of ARFl is not critical for its ences among ARFs appear to be concentrated near the amino action as a GTP-dependent activatorof cholera toxin.
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