Previous Article | Next Article ![]()
Mol Cell Biol, March 1998, p. 1652-1659, Vol. 18, No. 3
Departments of Medicine and Pharmacology,
Division of Cardiovascular Diseases, Mayo Clinic, Mayo Foundation,
Rochester, Minnesota 55905,1 and
Howard
Hughes Medical Institute, Harvard Medical School, Boston,
Massachusetts 021152
Received 10 October 1997/Returned for modification 24 November
1997/Accepted 12 December 1997
Structurally unique among ion channels, ATP-sensitive
K+ (KATP) channels are essential in coupling
cellular metabolism with membrane excitability, and their activity can
be reconstituted by coexpression of an inwardly rectifying
K+ channel, Kir6.2, with an ATP-binding cassette protein,
SUR1. To determine if constitutive channel subunits form a physical complex, we developed antibodies to specifically label and
immunoprecipitate Kir6.2. From a mixture of Kir6.2 and SUR1 in
vitro-translated proteins, and from COS cells transfected with both
channel subunits, the Kir6.2-specific antibody coimmunoprecipitated 38- and 140-kDa proteins corresponding to Kir6.2 and SUR1, respectively.
Since previous reports suggest that the carboxy-truncated Kir6.2 can form a channel independent of SUR, we deleted 114 nucleotides from the
carboxy terminus of the Kir6.2 open reading frame (Kir6.2
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Evidence for Direct Physical Association between a K+
Channel (Kir6.2) and an ATP-Binding Cassette Protein (SUR1) Which
Affects Cellular Distribution and Kinetic Behavior of an
ATP-Sensitive K+ Channel
C37). Kir6.2
C37 still coimmunoprecipitated with SUR1, suggesting that the
distal carboxy terminus of Kir6.2 is unnecessary for subunit association. Confocal microscopic images of COS cells transfected with Kir6.2 or Kir6.2
C37 and labeled with fluorescent antibodies revealed unique honeycomb patterns unlike the diffuse
immunostaining observed when cells were cotransfected with Kir6.2-SUR1
or Kir6.2
C37-SUR1. Membrane patches excised from COS cells
cotransfected with Kir6.2-SUR1 or Kir6.2
C37-SUR1 exhibited
single-channel activity characteristic of pancreatic KATP
channels. Kir6.2
C37 alone formed functional channels with
single-channel conductance and intraburst kinetic properties similar to
those of Kir6.2-SUR1 or Kir6.2
C37-SUR1 but with reduced burst
duration. This study provides direct evidence that an inwardly
rectifying K+ channel and an ATP-binding cassette protein
physically associate, which affects the cellular distribution and
kinetic behavior of a KATP channel.
*
Corresponding author. Mailing address: Guggenheim 7, Mayo Clinic, Rochester, MN 55905. Phone: (507) 284-2747. Fax: (507)
284-9111. E-mail: terzic.andre{at}mayo.edu.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|