title: Expression of biologically active fusion genes encoding the common alpha subunit and the follicle-stimulating hormone beta subunit. Role of a linker sequence.
abstract: The gonadotropin/thyrotropin hormone family is characterized by a heterodimeric structure composed of a common alpha subunit noncovalently linked to a hormone-specific beta subunit. The conformation of the heterodimer is essential for controlling secretion, hormone-specific post-translational modifications, and signal transduction. Structure-function studies of follicle-stimulating hormone (FSH) and the other glycoprotein hormones are often hampered by mutagenesis-induced defects in subunit combination. Thus, the ability to overcome the limitation of subunit assembly would expand the range of structure-activity relationships that can be performed on these hormones. Here we converted the FSH heterodimer to a single chain by genetically fusing the carboxyl end of the FSH beta subunit to the amino end of the alpha subunit in the presence or absence of a linker sequence. In the absence of the CTP linker, the secretion rate was decreased over 3-fold. Unexpectedly, however, receptor binding/signal transduction was unaffected by the absence of the linker. These data show that the single-chain FSH was secreted efficiently and is biologically active and that the conformation determinants required for secretion and biologic activity are not the same.
authors.affiliation: Department of Molecular Biology & Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: T
authors.initials: T
authors.lastname: Sugahara
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Kudo
authors.forename: D
authors.initials: D
authors.lastname: Ben-Menahem
authors.forename: M R
authors.initials: MR
authors.lastname: Pixley
authors.forename: A J
authors.initials: AJ
authors.lastname: Hsueh
authors.forename: I
authors.initials: I
authors.lastname: Boime
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006224:Cricetinae; D017931:DNA Primers; D005640:Follicle Stimulating Hormone / Q000235:genetics* / Q000378:metabolism; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics*
chemical_list: D017931:DNA Primers; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D011993:Recombinant Fusion Proteins; D005640:Follicle Stimulating Hormone