EXPRESSION OF KV1.1 DELAYED RECTIFIER POTASSIUM CHANNELS IN LEC MUTANT CHINESE-HAMSTER OVARY CELL-LINES REVEALS A ROLE FOR SIALIDATION IN CHANNEL FUNCTION

Kv1.1 potassium (K+) channels contain significant amounts of negativel y charged sialic acids, To examine the role of sialidation in K+ chann el function. Chinese hamster ovary cell lines deficient in glycosylati on (Lee mutants) were transfected with rat brain Kv1.1 cDNA, The K+ ch annel was functionally expressed in all cell lines, but the voltage de pendence of activation (V-1/2) was shifted to more positive voltages a nd the activation kinetics were slower in the mutant cell lines compar ed with control, A similar positive shift in VM was recorded in contro l cells expressing Kv1.1 following treatment with sialidase or by rais ing extracellular Ca2+, In contrast, these treatments had little or no effect on the Lec mutants, which indicates that channel sialic acids appear to be the negative surface charges sensitive to Ca2+, The data suggest that sialic acid addition modifies Kv1.1 channel function, pos sibly by influencing the local electric field detected by its voltage sensor, but that these carbohydrates are not required for cell surface expression.