Differences between the deep pores of K+ channels determined by an interacting pair of nonpolar amino acids.
The pore of a chimeric K+ channel, CHM, differed from its parental host channel, Kv2.1, by 9 amino acids. Four were located in a putative deep region and 5 in a nearby outer mouth. Point reversions were without restorative effects, and reversions V369I or L374V in the deep pore produced novel phenotypes. Among double mutations, only V369I and L374V were effective in restoring the Kv2.1 pore phenotype. Adding a change in charge at Q382K in the outer pore fully restored the parental phenotype. Thus, the pore appears to have an inner, deep region where ions such as K+ and TEA+ may be regulated by nonpolar residues and an outer region where ions may be regulated by charged residues.
Kirsch
G E
GE
Department of Anesthesiology, Baylor College of Medicine, Houston, Texas 77030.
Drewe
J A
JA
Hartmann
H A
HA
Taglialatela
M
M
de Biasi
M
M
Brown
A M
AM
Joho
R H
RH
D000595:Amino Acid Sequence; D000818:Animals; D004553:Electric Conductivity; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology*; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D013757:Tetraethylammonium Compounds / Q000378:metabolism; D014982:Xenopus laevis
D015221:Potassium Channels; D011994:Recombinant Proteins; D013757:Tetraethylammonium Compounds; D011188:Potassium