Multiple mRNA isoforms encoding the mouse cardiac Kv1-5 delayed rectifier K+ channel.
The mouse Kv1-5 K+ channel cDNA has been cloned from heart. This channel was highly expressed in heart and, to a lesser extent, in other tissues, including brain and thymus. Two alternatively spliced isoforms were found. The longer form encoded a 602-amino acid protein, while in the short form (Kv1-5 delta 5'), the first 200 amino acids lying upstream the transmembrane segment S1 were deleted. RNase protection experiments showed that both Kv1-5 mRNA isoforms are present in the mouse tissues examined, the longer form being predominant. The short mRNA (Kv1-5 delta 5') arose by an unusual splicing event within the exonic sequence. An additional short cDNA clone (Kv1-5 delta 3') that codes for a carboxyl-terminal truncated protein has been isolated. The gene coding sequence contained a single exon and has been mapped on human chromosome 12 (p13) and on mouse chromosome 6 (band F). Expression in Xenopus oocytes revealed that the long (Kv1-5) and the amino-terminal deleted (Kv1-5 delta 5') isoforms elicited similar K+ currents with a drastically decreased efficacy for Kv1-5 delta 5'. The carboxyl-terminal truncated Kv1-5 delta 3' clone was not functional but inhibited the expression of the long isoform.
Attali
B
B
Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.
Lesage
F
F
Ziliani
P
P
Guillemare
E
E
Honoré
E
E
Waldmann
R
R
Hugnot
J P
JP
Mattéi
M G
MG
Lazdunski
M
M
Barhanin
J
J
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004274:DNA, Recombinant; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009865:Oocytes; D015221:Potassium Channels / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D014981:Xenopus
D004274:DNA, Recombinant; D015221:Potassium Channels; D012333:RNA, Messenger