Isolation and characterization of native activin B.
To examine whether activin binds to follistatin, an activin-binding protein, to form a complex in vivo, we attempted to purify activin-follistatin complex from porcine follicular fluid. Our results thus obtained indicated that almost equimolar amounts of activins A, AB, and B are present as a complex with follistatin in the follicular fluid. Reverse-phase high performance liquid chromatography of the purified complex yielded follistatin and activins A, AB, and B. The activity of the purified activin B was found to be significantly lower than those of other activins in various assay systems such as stimulation of follicle-stimulating hormone secretion, induction of erythrodifferentiation, and potentiation of expression of gonadotropin receptors on ovarian cells. Moreover, binding of 125I-activin A to erythroleukemic cells which are activin-responsive was competed by activin B with approximately 10-fold lower potency compared with other activins. In contrast to these results, activin B was proved to have a potent Xenopus mesoderm-inducing activity, comparable with that of other activins. This indicates that, unlike activins A and AB, activin B can only elicit mesoderm-inducing activity and cannot function in other biological systems, suggesting a specific role of activin B in early development and unknown biological functions.
Nakamura
T
T
Frontier Research Program, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Asashima
M
M
Eto
Y
Y
Takio
K
K
Uchiyama
H
H
Moriya
N
N
Ariizumi
T
T
Yashiro
T
T
Sugino
K
K
Titani
K
K
D028341:Activins; D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D038681:Follistatin; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D007265:Inhibins / Q000378:metabolism; D007700:Kinetics; D004915:Leukemia, Erythroblastic, Acute; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides; D006080:Ovarian Follicle / Q000378:metabolism; D010455:Peptides / Q000302:isolation & purification* / Q000378:metabolism* / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011962:Receptors, FSH / Q000096:biosynthesis / Q000187:drug effects; D011974:Receptors, LH / Q000096:biosynthesis / Q000187:drug effects; D011994:Recombinant Proteins / Q000378:metabolism; D013552:Swine; D014407:Tumor Cells, Cultured
D038681:Follistatin; D006023:Glycoproteins; D009842:Oligopeptides; D010455:Peptides; D011962:Receptors, FSH; D011974:Receptors, LH; D011994:Recombinant Proteins; C044147:activin B; D028341:Activins; C048617:myelopeptides; D007265:Inhibins; D005640:Follicle Stimulating Hormone