PMID- 7711243
OWN - NLM
STAT- MEDLINE
DCOM- 19950518
LR  - 20191210
IS  - 0006-3495 (Print)
IS  - 1542-0086 (Electronic)
IS  - 0006-3495 (Linking)
VI  - 68
IP  - 1
DP  - 1995 Jan
TI  - Self-association accompanies inhibition of Ca-ATPase by thapsigargin.
PG  - 208-15
AB  - Recent studies have demonstrated a relationship between the activity of the 
      Ca-ATPase of sarcoplasmic reticulum and its state of self-association. In the 
      present study, the effects of thapsigargin (TG), a toxin that specifically 
      inhibits the Ca-ATPase of rabbit skeletal muscle sarcoplasmic reticulum membrane, 
      were studied by detecting the time-resolved phosphorescence anisotropy (TPA) 
      decay of the Ca-ATPase that had been labeled with the phosphorescent probe 
      erythrosin-isothiocyanate (ErITC). Anisotropy decays were fit to a function that 
      consisted of three exponential decays plus a constant background, as well as to a 
      function describing explicitly the uniaxial rotation of proteins in a membrane. 
      In the absence of TG, the anisotropy was best-fit by a model representing the 
      rotation of three populations, corresponding to different-sized oligomeric 
      species in the membrane. The addition of stoichiometric amounts of TG to the 
      Ca-ATPase promptly decreased the overall apparent rate of decay, indicating 
      decreased rotational mobility. A detailed analysis showed that the principal 
      change was not in the rates of rotation but rather in the population distribution 
      of the Ca-ATPase molecules among the different-sized oligomers. TG decreased the 
      proportion of small oligomers and increased the proportion of large ones. 
      Preincubation of the ErITC-SR in 1 mM Ca2+, which stabilizes the E1 conformation 
      relative to E2, was found to protect partially against the changes in the TPA 
      associated with the presence of the inhibitor. These results are consistent with 
      the hypothesis that TG inhibits the Ca-ATPase by stabilizing it in an E2-like 
      conformation, which promotes the formation of larger aggregates of the enzyme. 
      When combined with the effects of other inhibitors on the Ca-ATPase, these 
      results support a general model for the coupling of enzyme conformation and 
      self-association in this system.
FAU - Mersol, J V
AU  - Mersol JV
AD  - Department of Biochemistry, University of Minnesota Medical School, Minneapolis 
      55455.
FAU - Kutchai, H
AU  - Kutchai H
FAU - Mahaney, J E
AU  - Mahaney JE
FAU - Thomas, D D
AU  - Thomas DD
LA  - eng
GR  - GM27906/GM/NIGMS NIH HHS/United States
GR  - GM50764/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biophys J
JT  - Biophysical journal
JID - 0370626
RN  - 0 (Isothiocyanates)
RN  - 0 (Macromolecular Substances)
RN  - 0 (Terpenes)
RN  - 67526-95-8 (Thapsigargin)
RN  - 73676-43-4 (erythrosine isothiocyanate)
RN  - EC 7.2.2.10 (Calcium-Transporting ATPases)
RN  - PN2ZH5LOQY (Erythrosine)
SB  - IM
MH  - Animals
MH  - Binding Sites
MH  - Biophysical Phenomena
MH  - Biophysics
MH  - Calcium-Transporting ATPases/*antagonists & inhibitors/chemistry/metabolism
MH  - Erythrosine/analogs & derivatives
MH  - In Vitro Techniques
MH  - Isothiocyanates
MH  - Luminescence
MH  - Macromolecular Substances
MH  - Muscle, Skeletal/drug effects/metabolism
MH  - Rabbits
MH  - Sarcoplasmic Reticulum/drug effects/metabolism
MH  - Terpenes/metabolism/*pharmacology
MH  - Thapsigargin
PMC - PMC1281678
EDAT- 1995/01/01 00:00
MHDA- 1995/01/01 00:01
PMCR- 1996/01/01
CRDT- 1995/01/01 00:00
PHST- 1995/01/01 00:00 [pubmed]
PHST- 1995/01/01 00:01 [medline]
PHST- 1995/01/01 00:00 [entrez]
PHST- 1996/01/01 00:00 [pmc-release]
AID - S0006-3495(95)80176-1 [pii]
AID - 10.1016/S0006-3495(95)80176-1 [doi]
PST - ppublish
SO  - Biophys J. 1995 Jan;68(1):208-15. doi: 10.1016/S0006-3495(95)80176-1.