Journal
JOURNAL OF GENERAL PHYSIOLOGY
Volume 120, Issue 3, Pages 437-446Publisher
ROCKEFELLER UNIV PRESS
DOI: 10.1085/jgp.20028621
Keywords
K+ current; K-ATP; PIP2; Kir6.2; ATP
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Funding
- NHLBI NIH HHS [HL54171, T32 HL07275, R01 HL054171, T32 HL007275] Funding Source: Medline
- NIDDK NIH HHS [P60 DK020579, P30 DK020579, DK20579] Funding Source: Medline
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Approximately half of the NH2 terminus of inward rectifier (Kir) channels can be deleted without significant change in channel function, but activity is lost when more than similar to30 conserved residues before the first membrane spanning domain (M1) are removed. Systematic replacement of the positive charges in the NH2 terminus of Kir6.2 with alanine reveals several residues that affect channel function when neutralized. Certain mutations (R4A, R5A, R16A, R27A, R39A, K47A, R50A, R54A, K67A) change open probability, whereas an overlapping set of mutants (R16A, R27A, K39A, K47A, R50A, R54A, K67A) change ATP sensitivity. Further analysis of the latter set differentiates mutations that alter ATP sensitivity as a consequence of altered open state stability (R16A, K39A, K67A) from those that may affect ATP binding directly (K47A, R50A, R54A). The data help to define the structural determinants of Kir channel function, and suggest possible structural motifs within the NH2 terminus, as well as the relationship of the NH2 terminus with the extended cytoplasmic COOH terminus of the channel.
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