Subnuclear distribution of the S-100 protein specific binding sites in rat brain.
Fractionation of isolated brain nuclei previously reacted with (125)I-labelled S-100 showed that most of the specifically bound radioactivity associated with the nuclear membranes and the nucleoli. Labelling of nucleoli, which indicates the entrance of (125)I-labelled S-100 into the nucleus, was observed at 37 percent C, but not at 0-4 percent C. When tested separately for (125)I-labelled S-100 specific binding, both the nuclear membranes and the nucleoli were found to bind (125)I-labelled S-100 in a biphasic manner, the binding displaying a high affinity and a low affinity component, as observed with intact nuclei. However, the binding to nuclear membranes was largely irreversible, while that to nucleoli was fully reversible after any association time.
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000648:ultrastructure*; D002458:Cell Fractionation; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000648:ultrastructure*; D005260:Female; D007700:Kinetics; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009685:Nuclear Envelope / Q000378:metabolism; D051381:Rats; D009418:S100 Proteins / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D009418:S100 Proteins