title: Processing of transforming growth factor beta 1 precursor by human furin convertase.
abstract: Proteolytic processing of the transforming growth factor beta precursor (pro-TGF beta) is an essential step in the formation of the biologically active TGF beta homodimeric protein (TGF beta). The 361-amino-acid precursor pro-TGF beta 1 has within its primary structure the R-H-R-R processing signal found in many constitutively secreted precursor proteins and potentially recognized by members of the mammalian convertase family of endoproteases. To determine whether cleavage of pro-TGF beta 1 can be achieved by the furin convertase in vitro, purified precursor was incubated in the presence of a truncated/secreted form of the enzyme. Immunoblots showed that the 55-kDa pro-TGF beta 1 was converted into the 44 and 12.5 kDa bands corresponding to the pro-region and the mature monomer, respectively. Treatment of pro-TGF beta 1 with furin resulted in a 5-fold increase in the production of biologically active TGF beta 1. Furthermore, when expressed in the furin-deficient LoVo cells, no processing of pro-TGF beta 1 was observed. In contrast, efficient processing was observed when pro-TGF beta was coexpressed with the furin convertase. Collectively, these results provide evidence that in our experimental systems the TGF beta 1 precursor is efficiently and correctly processed by human furin thus permitting release of the biologically active peptide.
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Quebec, Canada.
authors.forename: C M
authors.initials: CM
authors.lastname: Dubois
authors.forename: M H
authors.initials: MH
authors.lastname: Laprise
authors.forename: F
authors.initials: F
authors.lastname: Blanchette
authors.forename: L E
authors.initials: LE
authors.lastname: Gentry
authors.forename: R
authors.initials: R
authors.lastname: Leduc
mesh_terms: D000595:Amino Acid Sequence; D016384:Consensus Sequence; D045683:Furin; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D013381:Subtilisins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D011498:Protein Precursors; D016212:Transforming Growth Factor beta; D013381:Subtilisins; D045683:Furin