Cloning of a novel alpha 1-subunit of the voltage-dependent calcium channel from the beta-cell.
Mol Endocrinol
; 6(12): 2143-52, 1992 Dec.
Article
em En
| MEDLINE
| ID: mdl-1337146
ABSTRACT
To study the molecular regulation of voltage-dependent Ca2+ channels (VDCCs) in the beta-cell, we have cloned a cDNA for the alpha 1-subunit from a hamster insulin-secreting cell line (HIT-T15). The cDNA (HCa3a) encodes a 1610-amino acid protein with four repeating membrane domains and an overall structure characteristic of other alpha 1-subunits. Although the cDNA shows a high degree of sequence homology (97%) with a rat brain alpha 1-subunit (RB alpha 1), the C-terminal 15 amino acids of HCa3a share no similarity with any cloned alpha 1 protein. High stringency Northern blot analysis revealed a single transcript of approximately 8.6 kilobases in HIT cells and hamster pancreas. A similarly sized species was detected in hamster brain, heart, and skeletal muscle. Using polymerase chain reaction and a primer set unique to HCa3a, this alpha 1 isoform was found to be expressed in islet cell lines derived from rat, mouse, and hamster. The HIT cell alpha 1-subunit is also expressed in discrete regions of the rat central nervous system, including the cortex, cerebellum, hypothalamus, and brain stem. The expression of two alpha 1 isoforms (HCa3a and cardiac) in the HIT cell underscores the possible complexity of VDCCs in the regulation of beta-cell signal transduction. With its widespread tissue distribution, HCa3a does not conform to the current classification system used for L-type VDCCs; this suggests that an alternative system of classification is required.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canais de Cálcio
/
Ilhotas Pancreáticas
Limite:
Animals
Idioma:
En
Revista:
Mol Endocrinol
Assunto da revista:
BIOLOGIA MOLECULAR
/
ENDOCRINOLOGIA
Ano de publicação:
1992
Tipo de documento:
Article