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J Nakai

Publications and source records attributed to J Nakai.

At least 37 records · Page 2Linked to original sources
PubMed1991

Primary structure and functional expression from complementary DNA of a brain calcium channel.

The primary structure of a voltage-dependent calcium channel from rabbit brain has been deduced by cloning and sequencing the complementary DNA. Calcium channel activity expressed from the cDNA is dramatically increased by coexpression of the alpha 2 and beta subunits, known to be associated with the dihydropyridine receptor. This channel is a high voltage-activated calcium channel that is insensitive both to nifedipine and to omega-conotoxin. We suggest that it is expressed predominantly in cerebellar Purkinje cells and granule cells.

Amino Acid Sequence↗
PubMed1990

Primary structure and functional expression from cDNA of the cardiac ryanodine receptor/calcium release channel.

The sequence of 4968 (or 4976 with an insertion) amino acids composing the ryanodine receptor from rabbit cardiac sarcoplasmic reticulum has been deduced by cloning and sequencing the cDNA. This protein is homologous in amino acid sequence and shares characteristic structural features with the skeletal muscle ryanodine receptor. Xenopus oocytes injected with mRNA derived from the cardiac ryanodine receptor cDNA exhibit Ca2(+)-dependent Cl- current in response to caffeine, which indicates the formation of functional calcium release channels. RNA blot hybridization analysis with a probe specific for the cardiac ryanodine receptor mRNA shows that the stomach and brain contain a hybridizable RNA species with a size similar to that of the cardiac mRNA. This result, in conjunction with cloning and analysis of partial cDNA sequences, suggests that the brain contains a cardiac type of ryanodine receptor mRNA.

Amino Acid Sequence↗
PubMed1989

Selective effector coupling of muscarinic acetylcholine receptor subtypes.

Attempts have been made by means of recombinant DNA technology to understand the molecular basis of the functional heterogeneity of the muscarinic acetylcholine receptor (mAChR). Molecularly defined mAChR subtypes have been produced from the cloned DNAs in Xenopus oocytes and NG108-15 neuroblastoma-glioma hybrid cells as transient and stable expression systems, respectively, and agonist-induced cellular responses have been examined. The results obtained provide evidence that mAChR subtypes are selectively coupled with different effector systems, albeit not exclusively.

Animals↗
PubMed1988

Location of a region of the muscarinic acetylcholine receptor involved in selective effector coupling.

Chimaeric muscarinic acetylcholine receptors (mAChR) in which corresponding portions of mAChR I and mAChR II are replaced with each other have been produced in Xenopus oocytes by expression of cDNA constructs encoding them. Functional analysis of the chimaeric mAChRs indicates that a region mostly comprising the putative cytoplasmic portion between the proposed transmembrane segments V and VI is involved in selective coupling of mAChR I and mAChR II with different effector systems. In contrast, the exchange of this region between mAChR I and mAChR II does not significantly affect the antagonist binding properties of the two mAChR subtypes.

Animals↗
PubMed1988

Different sensitivities to agonist of muscarinic acetylcholine receptor subtypes.

Muscarinic acetylcholine receptor (mAChR) III expressed in Xenopus oocytes, like mAChR I, mediates activation of a Ca2+-dependent Cl- current, whereas mAChR IV, like mAChR II, principally induces activation of Na+ and K+ currents in a Ca2+-independent manner. mAChR III has a sensitivity to agonist of about one order of magnitude higher than that of mAChR I in mediating the Ca2+-dependent current response in Xenopus oocytes and in stimulating phosphoinositide hydrolysis in NG108-15 neuroblastoma-glioma hybrid cells. The agonist-binding affinity of mAChR III is also about one order of magnitude higher than that of mAChR I.

Acetylcholine↗
PubMed1988

Rings of negatively charged amino acids determine the acetylcholine receptor channel conductance.

The structure-function relationship of the nicotinic acetylcholine receptor (AChR) has been effectively studied by the combination of complementary DNA manipulation and single-channel current analysis. Previous work with chimaeras between the Torpedo californica and bovine AChR delta-subunits has shown that the region comprising the hydrophobic segment M2 and its vicinity contains an important determinant of the rate of ion transport through the AChR channel. It has also been suggested that this region is responsible for the reduction in channel conductance caused by divalent cations and that segment M2 contributes to the binding site of noncompetitive antagonists. To identify those amino acid residues that interact with permeating ions, we have introduced various point mutations into the Torpedo AChR subunit cDNAs to alter the net charge of the charged or glutamine residues around the proposed transmembrane segments. The single-channel conductance properties of these AChR mutants expressed in Xenopus laevis oocytes indicate that three clusters of negatively charged and glutamine residues neighbouring segment M2 of the alpha-, beta-, gamma- and delta-subunits, probably forming three anionic rings, are major determinants of the rate of ion transport.

Amino Acid Sequence↗
PubMed1966

[Neurogenesis].

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Animals↗