Properties of a second sensory receptor protein in Halobacterium halobium phototaxis
A second slow-cycling retinylidene protein, in addition to slow-cycling (sensory) rhodopsin (SR), can be bleached with hydroxylamine and regenerated with all-trans retinal in photosensory signaling Halobacterium halobium membranes. Flash photolysis shows this protein undergoes a photochemical reaction cycle characterized by photoconversion of its ground state (lambda max 480 nm) to a species with lambda max less than or equal to 360 nm, which thermally regenerates the 480-nm species with a t1/2 of 260 msec at 25 degrees C, under conditions in which SR photocycles at 650 msec in the same membranes. Mutants characterized with respect to their phototaxis behavior are identified which contain SR and the 480-nm pigment, the latter ranging from undetectable to a concentration equal to that of SR. Receptor mutants lacking all phototaxis sensitivity lack both of the photochemically reactive proteins. The mutant properties contribute to an accumulation of behavioral and spectroscopic evidence that the 480-nm pigment is a second sensory photoreceptor in H. halobium. NaDodSO4-polyacrylamide gel electrophoresis of (/sup 3/H)retinal-labeled membrane proteins from the mutants indicates SR and the 480-nm pigment contain distinct chromophoric polypeptides differing in their migration rates. The data implicate polypeptides of 25,000 Mr and 23,000 Mr as retinal-binding polypeptides of SR and the 480-nm protein, respectively.
- Research Organization:
- Albert Einstein College of Medicine, Bronx, NY (USA)
- OSTI ID:
- 6994804
- Journal Information:
- Proteins; (United States), Journal Name: Proteins; (United States) Vol. 1:3; ISSN PSFGE
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CARBOXYLIC ACID ESTERS
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTROPHORESIS
ESTERS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MEMBRANE PROTEINS
MEMBRANES
MOLECULAR WEIGHT
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC MEMBRANES
PIGMENTS
PROTEINS
RETINOIC ACID
RHODOPSIN
TRACER TECHNIQUES
TRITIUM COMPOUNDS