PHOSPHORYLATION OF SYNAPSIN-I AND MARCKS IN NERVE-TERMINALS IS MEDIATED BY CA2-GI SENSITIVE CA2+ CHANNEL WHICH IS COUPLED TO GLUTAMATE EXOCYTOSIS( ENTRY VIA AN AGA)
Et. Coffey et al., PHOSPHORYLATION OF SYNAPSIN-I AND MARCKS IN NERVE-TERMINALS IS MEDIATED BY CA2-GI SENSITIVE CA2+ CHANNEL WHICH IS COUPLED TO GLUTAMATE EXOCYTOSIS( ENTRY VIA AN AGA), FEBS letters, 353(3), 1994, pp. 264-268
Ca2+ entry is a prerequisite for both exocytosis and the phosphorylati
on of synapsin I and MARCKS proteins in mammalian cerebrocortical syna
ptosomes. The novel spider toxin Aga-GI completely blocks KCl-evoked g
lutamate exocytosis but only partially inhibits KCl-evoked cytoplasmic
Ca2+ elevations, thus revealing at least two pathways for KCl-induced
Ca2+ entry. Aga-GI completely attenuates KCl-induced phosphorylation
of synapsin I and MARCKS proteins. We therefore conclude that both exo
cytosis and the phosphorylation of synapsin I and MARCKS proteins are
specifically coupled to Ca2+ entry via a subset of voltage dependent C
a2+ channels at the nerve terminal which are sensitive to Aga-GI.