Molecular characterization of a voltage-gated potassium channel expressed in rat testis.
Potassium (K(+)) channels are present in both mammalian testis and spermatozoa. Immunofluorescent detection of sperm-bound biotinylated charybdotoxin, an inhibitor of Ca(2+)-activated and of delayed rectifier K(+) channels, indicated that these ion channels are uniformly distributed over the surface of both heads and tails of unfixed rat epididymal spermatozoa. Reverse transcription-polymerase chain reaction (RT-PCR) analysis on rat testis RNA with PCR primers, based on known nucleotide sequences of different classes of K(+) channels, amplified sequences homologous to delayed rectifier K(+) channels. In-situ RT-PCR on rat testis sections showed that these K(+) channel transcripts are present in the cytoplasm of primary spermatocytes and post-meiotic elongating spermatids. Northern blot analysis of various rat tissues identified multiple K(+) channel transcripts, some of which were observed only in testis. An attempt to obtain a full length rat testis K(+) channel cDNA sequence gave an assembled sequence of 2693 base pairs with >90% homology to a delayed rectifier K(+) channel, Kv1.3. A method for rapid amplification of cDNA ends was employed to amplify the 5' sequences of the rat testis cDNA but a unique sequence could not be obtained. DNA sequencer traces suggest that multiple related K(+) channels which differed at their 5' ends were amplified in rat testis.
Jacob
A
A
Department of Obstetrics and Gynecology, North Shore University Hospital-New York University School of Medicine, Manhasset, New York 11030, USA.
Hurley
I R
IR
Goodwin
L O
LO
Cooper
G W
GW
Benoff
S
S
D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D018999:Charybdotoxin / Q000378:metabolism; D018076:DNA, Complementary; D051668:Delayed Rectifier Potassium Channels; D015870:Gene Expression; D051664:Kv1.3 Potassium Channel; D008297:Male; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013094:Spermatozoa / Q000378:metabolism; D013737:Testis / Q000378:metabolism
D020121:5' Untranslated Regions; D018076:DNA, Complementary; D051668:Delayed Rectifier Potassium Channels; C496975:Kcna3 protein, rat; D051664:Kv1.3 Potassium Channel; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018999:Charybdotoxin