The amino terminus of Slob, Slowpoke channel binding protein, critically influences its modulation of the channel.
The Drosophila Slowpoke calcium-dependent potassium channel (dSlo) binding protein Slob was discovered by a yeast two-hybrid screen using the carboxy-terminal tail region of dSlo as bait. Slob binds to and modulates the dSlo channel. We have found that there are several Slob proteins, resulting from multiple translational start sites and alternative splicing, and have named them based on their molecular weights (in kD). The larger variants, which are initiated at the first translational start site and are called Slob71 and Slob65, shift the voltage dependence of dSlo activation, measured by the whole cell conductance-voltage relationship, to the left (less depolarized voltages). Slob53 and Slob47, initiated at the third translational start site, also shift the dSlo voltage dependence to the left. In contrast, Slob57 and Slob51, initiated at the second translational start site, shift the conductance-voltage relationship of dSlo substantially to more depolarized voltages, cause an apparent dSlo channel inactivation, and increase the deactivation rate of the channel. These results indicate that the amino-terminal region of Slob plays a critical role in its modulation of dSlo.
Zeng
Haoyu
H
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Weiger
Thomas M
TM
Fei
Hong
H
Jaramillo
Angela M
AM
Levitan
Irwin B
IB
D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004330:Drosophila; D029721:Drosophila Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004594:Electrophysiology; D015640:Ion Channel Gating / Q000502:physiology; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008970:Molecular Weight; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*
D018076:DNA, Complementary; D029721:Drosophila Proteins; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; C111538:Slob protein, Drosophila; C494844:slo protein, Drosophila