Voltage-independent inhibition of P/Q-type Ca2+ channels in adrenal chromaffin cells via a neuronal Ca2+ sensor-1-dependent pathway involves Src family tyrosine kinase.

摘要: In common with many neurons, adrenal chromaffin cells possess distinct voltage-dependent and voltage-independent pathways for Ca2+ channel regulation. this study, the pathway was revealed by addition of naloxone suramin to remove tonic blockade currents via opioid purinergic receptors due autocrine feedback inhibition. This requires Ca2+-binding protein neuronal calcium sensor-1 (NCS-1). The pertussis toxin-sensitive, whereas largely toxin-insensitive. Characterization inhibition that it did not involve kinase C-dependent signaling but require activity a Src family tyrosine kinase. Two structurally inhibitors, 4-amino-5-(4-methylphenyl)7-(t-butyl)pyrazolo[3,4-d] pyrimidine (PP1) inhibitory peptide, increased currents, no further increase in Ca2+currents elicited suramin. addition, Src-like appeared act same as NCS-1. contrast, PP1 prevent facilitation strong pre-pulse depolarization indicating independent activity. PPI longer after P/Q-type blocker ω-agatoxin TK. α1A subunit channels immunoprecipitated from cell extracts found be phosphorylated PP1-sensitive manner endogenous kinases immunoprecipitate. A high molecular mass (around 220 kDa) form detected anti-phosphotyrosine, suggesting possible target action. These data demonstrate mechanism suggests may widely distributed