Yajamana Ramu

Learn More
Inward rectifiers are a class of K+ channels that can conduct much larger inward currents at membrane voltages negative to the K+ equilibrium potential than outward currents at voltages positive to it, even when K+ concentrations on both sides of the membrane are made equal. This conduction property, called inward rectification, enables inward rectifiers to(More)
Current through voltage-gated K+ channels underlies the action potential encoding the electrical signal in excitable cells. The four subunits of a voltage-gated K+ channel each have six transmembrane segments (S1-S6), whereas some other K+ channels, such as eukaryotic inward rectifier K+ channels and the prokaryotic KcsA channel, have only two transmembrane(More)
Voltage-gated ion channels in excitable nerve, muscle, and endocrine cells generate electric signals in the form of action potentials. However, they are also present in non-excitable eukaryotic cells and prokaryotes, which raises the question of whether voltage-gated channels might be activated by means other than changing the voltage difference between the(More)
A fundamental question about the gating mechanism of voltage-activated K+ (Kv) channels is how five positively charged voltage-sensing residues in the fourth transmembrane segment are energetically stabilized, because they operate in a low-dielectric cell membrane. The simplest solution would be to pair them with negative charges. However, too few(More)
Voltage-gated ion channels underlie rapid electric signaling in excitable cells. Electrophysiological studies have established that the N-terminal half of the fourth transmembrane segment ((NT)S4) of these channels is the primary voltage sensor, whereas crystallographic studies have shown that (NT)S4 is not located within a proteinaceous pore. Rather,(More)
Voltage-gated ion channels generate action potentials in excitable cells and help set the resting membrane potential in nonexcitable cells like lymphocytes. It has been difficult to investigate what kinds of phospholipids interact with these membrane proteins in their native environments and what functional impacts such interactions create. This problem(More)
Voltage-gated ion channels sense transmembrane voltage changes via a paddle-shaped motif that includes the C-terminal part of the third transmembrane segment (S3b) and the N-terminal part of the fourth segment ((NT)S4) that harbors voltage-sensing arginines. Here, we find that residue triplets in S3b and (NT)S4 can be deleted individually, or even in some(More)
Tertiapin (TPN), a small protein toxin originally isolated from honey bee venom, inhibits only certain eukaryotic inward-rectifier K(+) (Kir) channels with high affinity. We found that a short ( approximately 10 residues) sequence in Kir channels, located in the N-terminal part of the linker between the two transmembrane segments, is essential for(More)
Numerous mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR, a Cl(-) channel) disrupt salt and fluid transport and lead to the formation of thick mucus in patients' airways. Obstruction by mucus predisposes CF patients to chronic infections and inflammation, which become gradually harder to control and eventually fatal.(More)