Author/Editor		Križaj, David; Copenhagen, David R
Title		Compartmentalization of calcium extrusion mechanisms in the outer and inner segments of photoreceptors
Type		članek
Source		Neuron
Vol. and No.		Letnik 21, št. 1
Publication year		1998
Volume		str. 249-56
Language		eng
Abstract		Differential localization of calcium channel subtypes in divergent regions of individual neurons strongly suggests that calcium signaling and regulation could be compartmentalized. Region-specific expression of calcium extrusion transporters would serve also to partition calcium regulation within single cells. Little is known about selective localization of the calcium extrusion transporters, nor has compartmentalized calcium regulation within single neurons been studied in detail. Sensory neurons provide an experimentally tractable preparation to investigate this functional compartmentalization. We studied calcium regulation in the outer segment (OS) and inner segment/synaptic terminal (IS/ST) regions of rods and cones. We report these areas can function as separate compartments. Moreover, ionic, pharmacological, and immunolocalization results show that a Ca-ATPase, but not the Na+/K+, Ca2+ exchanger found in the OSs, extrudes calcium from the IS/ST region. The compartmentalization of calcium regulation in the photoreceptor outer and inner segments implies that transduction and synaptic signaling can be independently controlled. Similar separation of calcium-dependent functions is likely to apply in many types of neuron.
Descriptors		ANIMALS CALCIUM CALMODULIN CELL MEMBRANE HYDROGEN-ION CONCENTRATION INTRACELLULAR MEMBRANES LANTHANUM TISSUE DISTRIBUTION URODELA