Presence and possible role of the spliced isoform of the P2X1 receptor in rat vascular smooth muscle cells.
An alternatively spliced isoform of the P2X1 receptor (P2X1a) was cloned from rat mesenteric artery. The spliced isoform does not have the 27 amino acids that are in the middle of the putative extracellular loop domain of the P2X1 original subunit (P2X1). Reverse transcriptase polymerase chain reaction (RT-PCR) revealed co-localization of P2X1a mRNA and P2X1 mRNA in vascular and other smooth muscle tissues and heart, but not in the spinal cord. In HEK293 cells transfected with P2X1 cDNA, ATP (1 microM) evoked an inward current which strongly desensitized, and an intense signal for GFP (green fluorescent protein) fused with P2X1 was detected at the membrane. Neither of these results was obtained in HEK293 cells expressing P2X1a alone. The fluorescent GFP signal was detected at the membrane when GFP-fused P2X1a was co-expressed with P2X1, and no significant difference in the ATP-activated current was noted between cells expressing P2X1 and those coexpressing P2X1 and P2X1a. These results indicate that the 27-amino-acid sequence (175-201) is important for protein trafficking to the membrane and for the formation of a functional P2X1 receptor. Our results also show that P2X1a is transported to the membrane when P2X1a is co-expressed with P2X1, although the co-expression of P2X1a does not modify the channel's current properties.
Ohkubo
T
T
Department of Pharmacology, Fukuoka Dental College, Japan. ookut1@college.fdcnet.ac.jp
Yamazaki
J
J
Nakashima
Y
Y
Kitamura
K
K
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001488:Basilar Artery / Q000737:chemistry; D002460:Cell Line; D004553:Electric Conductivity; D004622:Embryo, Mammalian; D015870:Gene Expression; D006031:Glycosylation; D006801:Humans; D007668:Kidney; D008297:Male; D008638:Mesenteric Arteries / Q000737:chemistry; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000737:chemistry*; D016296:Mutagenesis; D009206:Myocardium / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D058469:Receptors, Purinergic P2X; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014162:Transfection; D014649:Vas Deferens / Q000737:chemistry
D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X