Structural determinants in the interaction of Shaker inactivating peptide and a Ca(2+)-activated K+ channel.
Shaker B inactivating peptide (BP) binds to its receptor in maxi KCa channels obstructing the flow of ions through them. The interaction between KCa channels and BP mutants, with different net charge and hydrophobicity, revealed several structural features of the KCa channel internal mouth. Increasing BP net positive charge or decreasing the internal milieu ionic strength increased the affinity and rate of association, while increasing hydrophobicity augmented blocking times and had limited or no effect on on-rates. These results uncover (a) the presence of negative charges in or near the BP receptor and (b) the existence of a hydrophobic contact surface in the internal channel vestibule that is a structural constituent of the BP receptor in maxi KCa channels.
Toro
L
L
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
Ottolia
M
M
Stefani
E
E
Latorre
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001158:Arteries / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D003331:Coronary Vessels / Q000737:chemistry / Q000378:metabolism; D004563:Electrochemistry; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013552:Swine
D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D015221:Potassium Channels; C076103:Shaker B inactivating peptide; D002118:Calcium