These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Secondary structure analysis of the putative membrane-associated domains of the inward rectifier K+ channel ROMK1.
    Author: Brazier SP, Ramesh B, Haris PI, Lee DC, Srai SK.
    Journal: Biochem J; 1998 Oct 15; 335 ( Pt 2)(Pt 2):375-80. PubMed ID: 9761737.
    Abstract:
    The inward rectifier K+ channels contain two putative membrane-spanning domains per subunit (M1, M2) and a 'pore' (P) region, which is similar to the H5 domain of voltage-gated K+ channels. Here we have used Fourier transform infrared (FTIR) and CD spectroscopy to analyse the secondary structures of synthetic peptides corresponding to the M1, M2 and P regions of ROMK1 in aqueous solution, in organic solvents and in phospholipid membranes. A previous CD study was unable to provide any structural data on a similar P peptide [Ben-Efraim and Shai (1997) Biophys. J. 72, 85-96]. However, our FTIR and CD spectroscopic analyses indicate that this peptide adopts an alpha-helical structure when reconstituted into dimyristoyl phosphatidylcholine vesicles and lysophosphatidyl choline (LPC) micelles as well as in trifluoroethanol (TFE) solvent. This result is in good agreement with a previous study on a peptide corresponding to the pore domain of a voltage-gated K+ channel [Haris, Ramesh, Sansom, Kerr, Srai and Chapman (1994) Protein Eng. 7, 255-262]. FTIR spectra of the M1 peptide in LPC micelles displayed a strong absorbance characteristic of an intermolecular beta-sheet structure, suggesting aggregation of the M1 peptide. Sucrose gradient centrifugation was used to separate aggregated peptide from peptide incorporated into micelles in an unaggregated manner; subsequent analysis by FTIR suggested that the M1 peptide adopted an alpha-helical structure when incorporated into phospholipid membranes. FTIR and CD spectra of the M2 peptide in phospholipids and high concentrations of TFE suggest that this peptide adopts an alpha-helical structure. The structural data obtained in these experiments have been used to propose a model for the structure of the membrane-associated core (M1-P-M2) of the inward rectifier K+ channel protein.
    [Abstract] [Full Text] [Related] [New Search]