Properties of the pH-sensitive site that controls the lambda max of Limulus metarhodopsin.


Journal Article

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.

Full Text

Cited Authors

  • Lisman, JE; Schulman, S; Sheline, Y; Brown, PK

Published Date

  • February 1, 1981

Published In

Volume / Issue

  • 77 / 2

Start / End Page

  • 191 - 203

PubMed ID

  • 7264596

Pubmed Central ID

  • 7264596

International Standard Serial Number (ISSN)

  • 0022-1295

Digital Object Identifier (DOI)

  • 10.1085/jgp.77.2.191


  • eng

Conference Location

  • United States