Abstract
A detailed characterization of the inositol 1,4,5-trisphosphate (IP3) receptor in rat basophilic leukemia (RBL) cells, a neoplastic mast cell line, has been possible through the growth of solid RBL cell tumors which provide a rich source of IP3 receptor. Equilibrium binding studies show a 1.6 ± 0.1 pmol/mg of protein maximal binding capacity for [3H]IP3 at optimal Ca2+ (10 μM). The specificity of the RBL cell IP3 receptor towards phosphoinositides, ATP and heparin parallels those previously described with excitable and nonexcitable tissues. [3H]IP3 binding is slightly enhanced from < 1 nM to 10 μM Ca2+ and inhibited by > 10 μM Ca2+. Kinetic and equilibrium studies provide evidence for at least two classes or conformational states of binding sites with pico- and nanomolar affinities. At nM concentrations of IP3, neither binding to the IP3 receptor nor IP3-induced Ca2+ efflux from permeabilized cells demonstrates cooperativity. In contrast, at pM concentrations, IP3 binding kinetics deviate from simple mass action suggesting a complex interaction among binding sites for IP3 on the receptor-channel oligomer. The mechanism that regulate [3H]IP3 binding in RBL cells are unique when compared to what has been reported in other cells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 105-114 |
| Number of pages | 10 |
| Journal | BBA - Biomembranes |
| Volume | 1147 |
| Issue number | 1 |
| DOIs | |
| State | Published - Apr 8 1993 |
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Keywords
- Calcium store
- Inositol 1,4,5-trisphosphate
- Intracellular calcium regulation
- Mast cell
- RBL cell
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Cell Biology
Cite this
Regulation of inositol 1,4,5-trisphosphate receptors in rat basophilic leukemia cells. I. Multiple conformational states of the receptor in a microsomal preparation. / Mohr, Frederick C; Hershey, Panda E C; Zimányi, Ildikó; Pessah, Isaac N.
In: BBA - Biomembranes, Vol. 1147, No. 1, 08.04.1993, p. 105-114.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Regulation of inositol 1,4,5-trisphosphate receptors in rat basophilic leukemia cells. I. Multiple conformational states of the receptor in a microsomal preparation
AU - Mohr, Frederick C
AU - Hershey, Panda E C
AU - Zimányi, Ildikó
AU - Pessah, Isaac N
PY - 1993/4/8
Y1 - 1993/4/8
N2 - A detailed characterization of the inositol 1,4,5-trisphosphate (IP3) receptor in rat basophilic leukemia (RBL) cells, a neoplastic mast cell line, has been possible through the growth of solid RBL cell tumors which provide a rich source of IP3 receptor. Equilibrium binding studies show a 1.6 ± 0.1 pmol/mg of protein maximal binding capacity for [3H]IP3 at optimal Ca2+ (10 μM). The specificity of the RBL cell IP3 receptor towards phosphoinositides, ATP and heparin parallels those previously described with excitable and nonexcitable tissues. [3H]IP3 binding is slightly enhanced from < 1 nM to 10 μM Ca2+ and inhibited by > 10 μM Ca2+. Kinetic and equilibrium studies provide evidence for at least two classes or conformational states of binding sites with pico- and nanomolar affinities. At nM concentrations of IP3, neither binding to the IP3 receptor nor IP3-induced Ca2+ efflux from permeabilized cells demonstrates cooperativity. In contrast, at pM concentrations, IP3 binding kinetics deviate from simple mass action suggesting a complex interaction among binding sites for IP3 on the receptor-channel oligomer. The mechanism that regulate [3H]IP3 binding in RBL cells are unique when compared to what has been reported in other cells.
AB - A detailed characterization of the inositol 1,4,5-trisphosphate (IP3) receptor in rat basophilic leukemia (RBL) cells, a neoplastic mast cell line, has been possible through the growth of solid RBL cell tumors which provide a rich source of IP3 receptor. Equilibrium binding studies show a 1.6 ± 0.1 pmol/mg of protein maximal binding capacity for [3H]IP3 at optimal Ca2+ (10 μM). The specificity of the RBL cell IP3 receptor towards phosphoinositides, ATP and heparin parallels those previously described with excitable and nonexcitable tissues. [3H]IP3 binding is slightly enhanced from < 1 nM to 10 μM Ca2+ and inhibited by > 10 μM Ca2+. Kinetic and equilibrium studies provide evidence for at least two classes or conformational states of binding sites with pico- and nanomolar affinities. At nM concentrations of IP3, neither binding to the IP3 receptor nor IP3-induced Ca2+ efflux from permeabilized cells demonstrates cooperativity. In contrast, at pM concentrations, IP3 binding kinetics deviate from simple mass action suggesting a complex interaction among binding sites for IP3 on the receptor-channel oligomer. The mechanism that regulate [3H]IP3 binding in RBL cells are unique when compared to what has been reported in other cells.
KW - Calcium store
KW - Inositol 1,4,5-trisphosphate
KW - Intracellular calcium regulation
KW - Mast cell
KW - RBL cell
UR - http://www.scopus.com/inward/record.url?scp=0027512103&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027512103&partnerID=8YFLogxK
U2 - 10.1016/0005-2736(93)90320-Y
DO - 10.1016/0005-2736(93)90320-Y
M3 - Article
C2 - 8385492
AN - SCOPUS:0027512103
VL - 1147
SP - 105
EP - 114
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
SN - 0005-2736
IS - 1
ER -