Toro L, Ottolia M, Stefani E, Latorre R
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
Biochemistry. 1994 Jun 14;33(23):7220-8. doi: 10.1021/bi00189a026.
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.
摇椅式B失活肽（BP）与其在大电导钙激活钾通道中的受体结合，阻碍离子通过这些通道流动。KCa通道与具有不同净电荷和疏水性的BP突变体之间的相互作用揭示了KCa通道内口的几个结构特征。增加BP的净正电荷或降低内部环境离子强度会增加亲和力和结合速率，而增加疏水性会延长阻断时间，对结合速率的影响有限或无影响。这些结果揭示了（a）BP受体中或其附近存在负电荷，以及（b）在内通道前庭存在一个疏水性接触表面，它是大电导钙激活钾通道中BP受体的结构组成部分。
