The Specific Interaction of S‐100 Protein with Synaptosomal Particulate Fractions. Evidence for the Formation of a Tight Complex Between S‐100 and Its Binding Sites

Abstract

The dissociation of the 125I-labeled S-100 specificially bound to rat synaptosomal particulate fractions (SYN) was studied under a variety of conditions after different association times. After a critical association time of about 20 min at 37.degree. C, the bound protein became progressively less accessible to the dissociating agents or conditions employed. The partial irreversibility of the 125I-labeled S-100 binding to SYN could be due to the formation of a tight complex between the protein and its synaptosomal sites. The data are discussed mainly in relation to the particulate-bound fraction of native S-100.