A study on two kinds of human minK proteins: Electrophysiological and pharmacological properties and incidence in the Chinese population

Background: There are two kinds of human minK proteins, differing from each other by one amino acid at the 38^th position (glycine for minK-G38 and serine for minK-S38). However, the functional significance of the minK polymorphism is not clear and neither is the allele incidence. Methods and Results: The electrophysiological and pharmacological properties of both minK proteins were studied by heterologous expression of minK proteins in Xenopus oocytes. The allele incidence was determined by polymerase chain reaction and restriction fragment analysis. Human minK cDNA was obtained by polymerase chain reaction using genomic DNA from leukocytes as the template. MinK mRNA was obtained by in vitro transcription reaction. The mRNA was injected into Xenopus oocytes for heterologous expression. The two-electrode voltage clamp technique was performed to investigate the current induced by minK protein. We found that the two minK proteins did not differ significantly with regard to their electrophysiological and pharmacological properties. Both minK proteins were inhibited by amiodarone and were not inhibited by quinidine, procainamide and sotalol. The incidences of both minK proteins were determined in 250 human subjects. We found that the allele incidences were 69% and 31% for minK-G38 and minK-S38, respectively. Conclusions: The two kinds of minK proteins had similar electrophysiological and pharmacological properties. The allele incidences were 69% and 31% for minK-G38 and minK-S38, respectively. This polymorphism can be used as a marker in genetic studies.