EXPRESSION OF PANULIRUS SHAKER POTASSIUM CHANNEL SPLICE VARIANTS

In Drosophila shaker voltage-dependent potassium channels, alternative splicing at the amino and carboxy termini produces currents with diff erent electrophysiological characteristics. We have cloned alternative ly spliced forms of shaker from the spiny lobster Panulirus interruptu s. Alternative exons were found at three sites of the gene: eight diff erent 5' exons, two alternative exons encoding the pore-forming P regi on, and an alternative 3' exon. Two of the different amino terminal sp lice forms were expressed with two alternatively spliced pore forms to produce channels with markedly different characteristics. One of the amino termini produced a channel with transient characteristics while the other produced a delayed rectifier-type channel. The effects of al ternative exons at the amino terminus and in the P region appear to be additive. Our results provide new information on the structural requi rements for rapid N-type inactivation.