PMID- 3022802
OWN - NLM
STAT- MEDLINE
DCOM- 19870109
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 25
IP  - 19
DP  - 1986 Sep 23
TI  - N-ethylmaleimide uncouples the glucagon receptor from the regulatory component of 
      adenylyl cyclase.
PG  - 5678-85
AB  - 125I-Glucagon binding to rat liver plasma membranes was composed of high- and 
      low-affinity components. N-Ethylmaleimide (NEM) and several other alkylating 
      agents induced a dose-dependent loss of high-affinity sites. This diminished the 
      apparent affinity of glucagon receptors for hormone without decreasing the 
      binding capacity of membranes. Solubilized hormone-receptor complexes were 
      fractionated as high molecular weight (Kav = 0.16) and low molecular weight (Kav 
      = 0.46) species by gel filtration chromatography; NEM or guanosine 
      5'-triphosphate (GTP) diminished the fraction of high molecular weight complexes, 
      suggesting that NEM uncouples glucagon receptor-N-protein complexes. Exposure of 
      intact hepatocytes to the impermeable alkylating reagent 
      p-(chloromercuri)benzenesulfonic acid failed to diminish the affinity of glucagon 
      receptors on subsequently isolated plasma membranes, indicating that the thiol 
      that affects receptor affinity is on the cytoplasmic side of the membrane. 
      Hormone binding to plasma membranes was altered by NEM even after receptors were 
      uncoupled from N proteins by GTP. These data suggest that a sensitive thiol group 
      that affects hormone binding resides in the glucagon receptor, which may be a 
      transmembrane protein. Alkylated membranes were fused with wild-type or cyc- S49 
      lymphoma cells to determine how alkylation affects the various components of the 
      glucagon-adenylyl cyclase system. Stimulation of adenylyl cyclase with fluoride, 
      guanylyl 5'-imidodiphosphate, glucagon, or isoproterenol was observed after 
      fusion of cyc- S49 cells [which lack the stimulatory, guanine nucleotide binding, 
      regulatory protein of adenylyl cyclase (Ns)] with liver membranes alkylated with 
      1.5 mM NEM.(ABSTRACT TRUNCATED AT 250 WORDS)
FAU - Lipson, K E
AU  - Lipson KE
FAU - Kolhatkar, A A
AU  - Kolhatkar AA
FAU - Dorato, A
AU  - Dorato A
FAU - Donner, D B
AU  - Donner DB
LA  - eng
GR  - AM 01045/AM/NIADDK NIH HHS/United States
GR  - AM 22121/AM/NIADDK NIH HHS/United States
GR  - CA 08748/CA/NCI NIH HHS/United States
GR  - etc.
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Receptors, Gastrointestinal Hormone)
RN  - 0 (Receptors, Glucagon)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - 9007-92-5 (Glucagon)
RN  - EC 3.6.1.- (GTP-Binding Proteins)
RN  - EC 4.6.1.1 (Adenylyl Cyclases)
RN  - O3C74ACM9V (Ethylmaleimide)
SB  - IM
MH  - Adenylyl Cyclases/isolation & purification/*metabolism
MH  - Animals
MH  - Cell Membrane/metabolism
MH  - Ethylmaleimide/*pharmacology
MH  - GTP-Binding Proteins/isolation & purification/*metabolism
MH  - Glucagon/metabolism
MH  - Guanosine Triphosphate/metabolism
MH  - Kinetics
MH  - Liver/*metabolism
MH  - Male
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Receptors, Gastrointestinal Hormone/isolation & purification/*metabolism
MH  - Receptors, Glucagon
EDAT- 1986/09/23 00:00
MHDA- 1986/09/23 00:01
CRDT- 1986/09/23 00:00
PHST- 1986/09/23 00:00 [pubmed]
PHST- 1986/09/23 00:01 [medline]
PHST- 1986/09/23 00:00 [entrez]
AID - 10.1021/bi00367a050 [doi]
PST - ppublish
SO  - Biochemistry. 1986 Sep 23;25(19):5678-85. doi: 10.1021/bi00367a050.