We have investigated the molecular mechanisms that produce different structural and functional behavior in the monomeric and trimeric forms of seminal vesicle protein no. 4, a protein with immunomodulatory, anti-inflamma-tory, and procoagulant activity secreted from the rat seminal vesicle epithelium. The monomeric and trimeric forms were characterized in solution by CD. Details of the self-association process and structural changes that accompany aggregation were investigated by different experimental approaches: trypsin proteolysis, sequence analysis, chemical modification, and computer modeling
