Rajnesh K. Sharma

Learn More
Atrial natriuretic factor (ANF) is a peptide hormone that is released from atria and regulates a number of physiological processes, including steroidogenesis in adrenal cortex and testes. The parallel stimulation of membrane guanylate cyclase and corticosterone production in isolated fasciculata cells of rat adrenal cortex has supported the hypothesis of a(More)
The membrane bound guanylyl cyclase (GC) photoreceptor membrane GC1 (ROS-GCI) of photoreceptor cells synthesizes cGMP, the intracellular transmitter of vertebrate phototransduction. The activity of ROS-GCI is controlled by small Ca(2+)-binding proteins, named GC-activating proteins (GCAPs). We identified and characterized two short regulatory regions(More)
The ROS-GC subfamily of membrane guanylate cyclases is at present represented by two members: ROS-GC1 and ROS-GC2. A unique functional feature of this subfamily is that it is intracellularly modulated in low Ca2+ concentration by calmodulin-like Ca(2+)-binding proteins termed GCAPs, 1 and 2, and the modulation is consistent with its linkage to(More)
This report defines the identity of a calcium-regulated membrane guanylate cyclase transduction system in the cilia of olfactory sensory neurons, which is the site of odorant transduction. The membrane fraction of the neuroepithelial layer of the rat exhibited Ca(2+)-dependent guanylate cyclase activity, which was eliminated by the addition of EGTA. This(More)
The mechanism by which the individual odor signals are translated into the perception of smell in the brain is unknown. The signal processing occurs in the olfactory system which has three major components: olfactory neuroepithelium, olfactory bulb, and olfactory cortex. The neuroepithelial layer is composed of ciliated sensory neurons interspersed among(More)
The relation between steroidogenesis induced by adrenocorticotropic hormone and the concentrations of adenosine 3',5'-monophosphate (cyclic AMP) and guanosine 3',5'-monophosphate (cyclic GMP) was studied at different time intervals in isolated adrenal cells. Submaximal and supramaximal steroidogenic concentrations of the hormone did not cause detectable(More)
Almost three decades of research in the field of photoreceptor guanylate cyclases are discussed in this review. Primarily, it focuses on the members of membrane-bound guanylate cyclases found in the outer segments of vertebrate rods. These cyclases represent a new guanylate cyclase subfamily, termed ROS-GC, which distinguishes itself from the peptide(More)
In contrast to the membrane guanylate cyclases which are stimulated by extracellular ligands, rod outer segment membrane guanylate cyclase (ROS-GC) activity is modulated intracellularly by calcium in two ways: one, where it is inhibited, and the other, where it is stimulated. The former way is linked to the phototransduction, and physiology of the second is(More)
In vertebrate retina, rod outer segment is the site of visual transduction. The inward cationic current in the dark-adapted outer segment is regulated by cyclic GMP. A light flash on the outer segment activates a cyclic GMP phosphodiesterase resulting in rapid hydrolysis of the cyclic nucleotide which in turn causes a decrease in the dark current.(More)
A native bovine calcium-modulated rod outer segment membrane guanylate cyclase (ROS-GC) has been cloned and reconstituted to show its linkage consistent to the process of phototransduction. In the present study, a second form of the membrane guanylate cyclase has been cloned from the bovine retina. This cyclase shares a high sequence identity with ROS-GC,(More)