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The GXGXG motif in the pI Cln protein is not important for the nucleotide sensitivity of the pI Cln ‐induced Cl − current in Xenopus oocytes
Author(s) -
Voets Thomas,
Buyse Gunnar,
Droogmans Guy,
Eggermont Jan,
Nilius Bernd
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00334-2
Subject(s) - pi , xenopus , nucleotide , chemistry , biochemistry , gene
It has been proposed that the pI Cln protein forms a nucleotide‐sensitive plasma membrane anion channel with a GXGXG motif being an essential component of the extracellular nucleotide‐binding site. To evaluate this hypothesis, we have performed voltage‐clamp experiments on Xenopus laevis oocytes injected with RNA encoding a rat mutant pI Cln in which the three glycines of the putative nucleotide‐binding site have been changed into alanines (G54A; G56A; G58A). The injected oocytes displayed outwardly rectifying anion currents, which were voltage‐dependently blocked by extracellular cAMP, but which were not affected by removal of extracellular Ca 2+ . Furthermore, the mutation did not affect the voltage‐dependent inactivation. We therefore conclude that there is no evidence in favour of an extracellular nucleotide‐binding site in pI Cln .