title: Distribution of SP1, immunoreactivity among different plasma proteins: real molecular heterogeneity or adsorption of SP1-beta to other plasma proteins?
abstract: Three SP1-containing factors from pooled term pregnancy sera were subjected to crossed immunoelectrophoresis. New patterns as far as electrophoretic mobilities and shapes of the immunoprecipitates were revealed. The appearance of an additional anodic radioimmunoassayable activity in agarose electrophoresis of mixed SP1-alpha and SP1-beta suggested a binding capacity of SP1-alpha for SP1-beta determinants. In the serum of a single patient at the third trimester of pregnancy we also found two SP1 variants, possessing little radioimmunological reactivity and with crossed immunoelectrophoretic characteristics quite different from those of the 'usual' alpha and beta SP1 forms. These results suggest that, in this particular case, the overall SP1 production cannot be evaluated by competitive binding assay and, that in general, SP1 is a complex antigen the heterogeneity of which can be determined following adsorption of some beta epitopes to another serum protein.
authors.affiliation: Institute of 2nd Clinic of Obstetrics and Gynecology, University of Rome La Sapienza, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pala
authors.forename: A
authors.initials: A
authors.lastname: Di Ruzza
authors.forename: G
authors.initials: G
authors.lastname: Rossetto
authors.forename: M
authors.initials: M
authors.lastname: Moro
authors.forename: R
authors.initials: R
authors.lastname: Strom
authors.forename: F
authors.initials: F
authors.lastname: Padula
authors.forename: E V
authors.initials: EV
authors.lastname: Cosmi
mesh_terms: D005260:Female; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D011247:Pregnancy; D011268:Pregnancy-Specific beta 1-Glycoproteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D011268:Pregnancy-Specific beta 1-Glycoproteins