1. The effect of rabbit anti-(pigeon erythrocyte) antibodies plus human complement on the concentration of intracellular free Ca2+ in sealed pigeon erythrocyte 'ghosts' was investigated with the photoprotein obelin. 2. The addition of human serum, as a source of complement, to 'ghosts' coated with antibody caused a rapid increase in intracellular free Ca2+ after a lag of 20-40 s, as detected by...

Acidosis leads to mechanical alternans (i.e., alternation of large and small contractions) in ferret papillary muscles. This alternation in the size of the contraction is paralleled by alternation in the size of the intracellular Ca2+ transient (monitored using the photoprotein aequorin). In isolated myocytes, the large contraction is accompanied by a prolonged action potential. Mechanical alte...

The source and sinks for the intracellular calcium released during fertilization were examined in single eggs from the sea urchin, Arbacia punctulata. Single eggs were microinjected with the calcium photoprotein, aequorin. The calcium-aequorin luminescence was measured with a microscope-photomultiplier or observed with a microscope-image intensifier-video system. In the normal egg a propagated ...

; Plants respond to various abiotic stimuli by activation and propagation of fast electrical signals, action potentials. To resolve the temporal increase in cytosolic Ca during the action potentials of higher plants, we regenerated transgenic potato plants that expressed the Ca photoprotein apoaequorin. These genetically engineered potato plants were used for simultaneous measurements of transi...

Utilization of light is crucial for the life cycle of many organisms. Also, many organisms can create light by utilizing chemical energy emerged from biochemical reactions. Being the most important structural units of the organisms, proteins play a vital role in the formation of light in the form of bioluminescence. Such photoproteins have been isolated and identified for a long time; the exact...

Green fluorescent proteins (GFPs) and calcium-activated photoproteins of the aequorin/clytin family, now widely used as research tools, were originally isolated from the hydrozoan jellyfish Aequora victoria. It is known that bioluminescence resonance energy transfer (BRET) is possible between these proteins to generate flashes of green light, but the native function and significance of this phe...

I discovered the green fluorescent protein GFP from the jellyfish Aequorea aequorea in 1961 as a byproduct of the Ca-sensitive photoprotein aequorin (Shimomura et al., 1962; Johnson et al., 1962), and identified its chromophore in 1979 (Shimomura, 1979). GFP was a beautiful protein but it remained useless for the next 30 years after the discovery. My story begins in 1945, the year the city of N...

Ever since it was shown that maintenance of muscle contraction required the presence of extracellular Ca(2+), evidence has accumulated that Ca(2+) plays a crucial role in excitation-contraction coupling. This culminated in the use of the photoprotein aequorin to demonstrate that [Ca(2+)](i) increased after depolarization but before contraction in barnacle muscle. Green fluorescent protein was e...

Proteorhodopsin (PR) is a retinal-binding bacterial integral membrane protein that functions as a light-driven proton pump. The gene encoding this photoprotein was originally discovered on a large genome fragment derived from an uncultured marine gamma-proteobacterium of the SAR86 group. Subsequently, many variants of the PR gene have been detected in marine plankton, via PCR-based gene surveys...