Abstract
A pH-sensitive site controls the lambda max of Limulus metarhodopsin. The properties of this site were examined using intracellular recordings of the early receptor potential (ERP) as a pigment assay. ERPs recorded over a range of extracellular pHs indicate that the apparent pK of the site is in the range of 8.3-8.6. Several lines of evidence indicate that the site responds directly to changes in extracellular pH (pHo) rather than to changes in intracellular pH(pHi) that follow as a secondary result of changing pHo : (a) the effect of changing pHo was rapid (less than 60 s); (b) when pHo was raised, the simultaneous rise in pHi, as measured with phenol red, was relatively small; (c) raising pHi by intracellular injection of pH 10 glycine buffer did not affect the site; and (d) the effect of changing pH0 could not be blocked by increasing the intracellular pH buffering capacity. It is concluded that the pH-sensitive site on metarhodopsin is on the extracellular surface of the plasma membrane.
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- ARMSTRONG C. M., BINSTOCK L. ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE. J Gen Physiol. 1965 May;48:859–872. doi: 10.1085/jgp.48.5.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BALL S., COLLINS F. D. Studies in vitamin A; reactions of retinene1 with amino compounds. Biochem J. 1949;45(3):304–307. doi: 10.1042/bj0450304. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown H. M., Meech R. W. Light induced changes of internal pH in a barnacle photoreceptor and the effect of internal pH on the receptor potential. J Physiol. 1979 Dec;297(0):73–93. doi: 10.1113/jphysiol.1979.sp013028. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Coles J. A., Brown J. E. Effects of increased intracellular pH-buffering capacity on the light response of Limulus ventral photoreceptor. Biochim Biophys Acta. 1976 Jun 4;436(1):140–153. doi: 10.1016/0005-2736(76)90226-1. [DOI] [PubMed] [Google Scholar]
- Fernandez H. R., Nickel E. E. Ultrastructural and molecular characteristics of crayfish photoreceptor membranes. J Cell Biol. 1976 Jun;69(3):721–732. doi: 10.1083/jcb.69.3.721. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUBBARD R., ST GEORGE R. C. The rhodopsin system of the squid. J Gen Physiol. 1958 Jan 20;41(3):501–528. doi: 10.1085/jgp.41.3.501. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hagins W. A., McGaughy R. E. Molecular and thermal origins of fast photoelectric effects in the squid retina. Science. 1967 Aug 18;157(3790):813–816. doi: 10.1126/science.157.3790.813. [DOI] [PubMed] [Google Scholar]
- Hubbell W. L., Fung B. K. The structure and chemistry of rhodopsin: relationship to models of function. Soc Gen Physiol Ser. 1979;33:17–25. [PubMed] [Google Scholar]
- Lisman J. E., Brown J. E. Effects of intracellular injection of calcium buffers on light adaptation in Limulus ventral photoreceptors. J Gen Physiol. 1975 Oct;66(4):489–506. doi: 10.1085/jgp.66.4.489. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lisman J. E., Sheline Y. Analysis of the rhodopsin cycle in limulus ventral photoreceptors using the early receptor potential. J Gen Physiol. 1976 Nov;68(5):487–501. doi: 10.1085/jgp.68.5.487. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lisman J. E., Strong J. A. The initiation of excitation and light adaptation in Limulus ventral photoreceptors. J Gen Physiol. 1979 Feb;73(2):219–243. doi: 10.1085/jgp.73.2.219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Narahashi T., Anderson N. C., Moore J. W. Tetrodotoxin does not block excitation from inside the nerve membrane. Science. 1966 Aug 12;153(3737):765–767. doi: 10.1126/science.153.3737.765. [DOI] [PubMed] [Google Scholar]
- Perrelet A., Baumann F. Evidence for extracellular space in the rhabdome of the honeybee drone eye. J Cell Biol. 1969 Mar;40(3):825–830. doi: 10.1083/jcb.40.3.825. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Woodhull A. M. Ionic blockage of sodium channels in nerve. J Gen Physiol. 1973 Jun;61(6):687–708. doi: 10.1085/jgp.61.6.687. [DOI] [PMC free article] [PubMed] [Google Scholar]