Protein kinase C regulates a vesicular class of calcium channels in the bag cell neurons of Aplysia

Leonard K. Kaczmarek. Protein kinase C regulates a vesicular has been shown to enhance current not by modulating the class of calcium channels in the bag cell neurons of Aplysia. J. activity of an already active calcium channel but by recruit-Neurophysiol. 80: 2514–2520, 1998. Protein kinase C (PKC) ing a previously inactive type of calcium channel (DeRiemer acutely increases calcium currents in Aplysia bag cell neurons by et al. 1985; Strong et al. 1987). recruiting calcium channels different from those constitutively ac- Patch-clamp analysis of bag cell neurons identified twotive in the plasma membrane. To study the mechanism of PKC types of calcium current, a basal current carried by a 12-pSregulation we previously identified two calcium channel a1-sub-channel constitutively present in the plasma membrane andunits expressed in bag cell neurons. One of these, BC-a1A, is a PKC-sensitive current carried by a 24-pS channel seenlocalized to vesicles concentrated primarily in somata and growth cones. We used antibodies to BC-a1A to analyze its expression in only after treatment of bag cell neurons with activators of the bag cell neurons of juvenile Aplysia at a developmental stage PKC (Strong et al. 1987). A unique feature of calcium at which PKC-sensitive calcium currents have previously been channel modulation in bag cell neurons is its sensitivity to shown to be low. We find that vesicular BC-a1A staining is gener- whole cell recording conditions. Unlike kinase-mediated ally reduced in juvenile bag cell neurons but that its expression modulation of calcium channels observed in other cell types,level can vary among juvenile animals. In 17 bag cell clusters recruitment is disrupted by the formation of whole cel