Sequence and functional expression in Xenopus oocytes of a human insulinoma and islet potassium channel

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.1.53· OSTI ID:5030939

Philipson, L H; Hice, R E; Schaefer, K; LaMendola, J; Bell, G I; Nelson, D J; Steiner, D F ^[1]

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1. Univ. of Chicago, IL (United States)

Regulation of insulin secretion involves the coordinated control of ion channels in the {beta}-cell membrane. The authors have isolated and characterized cDNA and genomic clones encoding a voltage-dependent K{sup +} channel isoform expressed in human islets and in a human insulinoma. This K{sup +} channel isoform, designated hPCN1, with a deduced amino acid sequence of 613 residues is related to the Shaker family of Drosophila K{sup +} channels. hPCN1 is homologous to two other human K{sup +} channel isoforms. They have isolated, hPCN2 and hPCN3, with 55% and 65% amino acid sequence identity, respectively. The electrophysiological characteristics of hPCN1 were determined after microinjuection of synthetic RNA into Xenopus oocytes. Two-microelectrode voltage-clamp recordings of oocytes injected with hPCN1 RNA revealed a voltage-dependent outward K{sup +} current that inactivated slowly with time. Outward currents were inhibited by 4-aminopyridine with a K{sub i} less that 0.01 mM and were relatively insensitive to tetraethylammonium ion or Ba{sup 2+}. A delayed rectifier K{sup +} channel such as hPCN1 could restore the resting membrane potential of {beta} cells after depolarization and thereby contribute to the regulation of insulin secretion.

• OSTI ID: 5030939
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:1; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
INSULIN
SECRETION
MEMBRANE PROTEINS
GENE REGULATION
RECEPTORS
AMINO ACID SEQUENCE
RECOMBINANT DNA
DNA SEQUENCING
AMPHIBIANS
DROSOPHILA
ELECTRIC POTENTIAL
GENE AMPLIFICATION
OOCYTES
PHOSPHORUS 32
PYRIDINES
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
AZINES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DIPTERA
DNA
FLIES
FRUIT FLIES
GERM CELLS
HETEROCYCLIC COMPOUNDS
HORMONES
INSECTS
INVERTEBRATES
ISOTOPES
LIGHT NUCLEI
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDE HORMONES
PHOSPHORUS ISOTOPES
PROTEINS
RADIOISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques