TY - JOUR
T1 - Kinetic Characterization of Ca2+ Transport in Synaptic Membranes
AU - Javors, M. A.
AU - Bowden, C. L.
AU - Ross, D. H.
PY - 1981/8
Y1 - 1981/8
N2 - Abstract: Lysed synaptosomal membranes were prepared from brain cortices of HA/ICR Swiss mice, and the ATP‐stimulated Ca2+ uptake, Ca2+‐stimulated Mg2+ ‐dependent ATPase activity, and the Ca2+‐stimulated acyl phosphorylation of these membranes were studied. The Km values for free calcium concentrations ([Ca2+]f) for these processes were 0.50 μM, 0.40 μM, and 0.31 μM, respectively. Two kinetically distinct binding sites for ATP were observed for the ATP‐stimulated Ca2+ uptake and the Ca2+‐stimulated Mg2+‐ATPase activity. The high‐affinity Km values for ATP for these two processes were 16.3 μM, and 28 μM, respectively. These results indicate that the processes studied operate in similar physiological concentration ranges for the substrates [Ca2+]f and ATP under identical assay conditions and, further, that these processes may be functionally coupled in the membrane.
AB - Abstract: Lysed synaptosomal membranes were prepared from brain cortices of HA/ICR Swiss mice, and the ATP‐stimulated Ca2+ uptake, Ca2+‐stimulated Mg2+ ‐dependent ATPase activity, and the Ca2+‐stimulated acyl phosphorylation of these membranes were studied. The Km values for free calcium concentrations ([Ca2+]f) for these processes were 0.50 μM, 0.40 μM, and 0.31 μM, respectively. Two kinetically distinct binding sites for ATP were observed for the ATP‐stimulated Ca2+ uptake and the Ca2+‐stimulated Mg2+‐ATPase activity. The high‐affinity Km values for ATP for these two processes were 16.3 μM, and 28 μM, respectively. These results indicate that the processes studied operate in similar physiological concentration ranges for the substrates [Ca2+]f and ATP under identical assay conditions and, further, that these processes may be functionally coupled in the membrane.
KW - ATP‐dependent Ca uptake
KW - Ca transport protein
KW - Cation transport
KW - Ca‐Mg‐ATPase activity
KW - Ca‐stimulated acyl phosphorylation
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U2 - 10.1111/j.1471-4159.1981.tb00466.x
DO - 10.1111/j.1471-4159.1981.tb00466.x
M3 - Article
C2 - 6114989
AN - SCOPUS:0019728940
SN - 0022-3042
VL - 37
SP - 381
EP - 387
JO - Journal of neurochemistry
JF - Journal of neurochemistry
IS - 2
ER -