ABSTRACT
The protein of origin in senile amyloid of the seminal vesicles has been identified in this study. Amyloid fibrils were isolated from frozen seminal vesicles in a pure form. Immunochemical and chemical studies revealed that a major polypeptide of 13 KDa represents an N-terminal fragment of semenogelin I (SgI). Similar polypeptides of SgI were isolated from formalin-fixed seminal vesicles containing amyloid. Although it had been reported previously that this material contained lactoferrin and it was suggested that lactoferrin was the protein of origin, the results of our studies revealed that lactoferrin was not present in significant amounts in pure amyloid fibrils. Since semenogelin I was identified as the protein of origin of senile seminal vesicle amyloid, we provisionally designate this entity as ASgI.
