TY - JOUR
T1 - Function of calmodulin in postsynaptic densities. III. Calmodulin-binding proteins of the postsynaptic density
AU - Carlin, R. K.
AU - Grab, D. J.
AU - Siekevitz, P.
PY - 1981
Y1 - 1981
N2 - A method has been developed for binding calmodulin, radioiodinated by the lactoperoxidase method, to denaturing gels and has been used to attempt to identify the calmodulin-binding proteins of cerebral cortex postsynaptic densities (PSDs). Calmodulin primarily bound to the major 51,000 M(r) protein in a saturatable manner; secondarily bound to the 60,000 M(r) region, 140,000 M(r) region, and 230,000 M(r) protein; and bound in lesser amounts to a number of other proteins. The major 51,000 M(r) calmodulin-binding protein is one of unknown identity. Binding of iodinated calmodulin to these proteins was blocked by EDTA, EGTA, chlorpromazine, and preincubation with unlabeled calmodulin. Calmodulin iodinated by the chloramine-T method, which inactivates calmodulin, did not bind to the PSD but bound nonspecifically to histone. Calmodulin did not bind to proteins from a variety of sources for which calmodulin interactions have not been found. Except for three proteins, all of the proteins of synaptic membranes that bind calmodulin could be accounted for by proteins of the PSD which are a part of the synaptic membrane fraction. The major 51,000 M(r) protein and the corresponding iodinated calmodulin binding were greatly reduced in cerebellar PSDs and this difference between cerebral cortex and cerebellar PSDs is discussed in light of the possible function of calmodulin in synaptic excitatory responses.
AB - A method has been developed for binding calmodulin, radioiodinated by the lactoperoxidase method, to denaturing gels and has been used to attempt to identify the calmodulin-binding proteins of cerebral cortex postsynaptic densities (PSDs). Calmodulin primarily bound to the major 51,000 M(r) protein in a saturatable manner; secondarily bound to the 60,000 M(r) region, 140,000 M(r) region, and 230,000 M(r) protein; and bound in lesser amounts to a number of other proteins. The major 51,000 M(r) calmodulin-binding protein is one of unknown identity. Binding of iodinated calmodulin to these proteins was blocked by EDTA, EGTA, chlorpromazine, and preincubation with unlabeled calmodulin. Calmodulin iodinated by the chloramine-T method, which inactivates calmodulin, did not bind to the PSD but bound nonspecifically to histone. Calmodulin did not bind to proteins from a variety of sources for which calmodulin interactions have not been found. Except for three proteins, all of the proteins of synaptic membranes that bind calmodulin could be accounted for by proteins of the PSD which are a part of the synaptic membrane fraction. The major 51,000 M(r) protein and the corresponding iodinated calmodulin binding were greatly reduced in cerebellar PSDs and this difference between cerebral cortex and cerebellar PSDs is discussed in light of the possible function of calmodulin in synaptic excitatory responses.
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M3 - Article
C2 - 6265467
AN - SCOPUS:0019863029
SN - 0021-9525
VL - 89
SP - 449
EP - 455
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 3
ER -