title: Murine serpin 2A is a redox-sensitive intracellular protein.
abstract: Murine serpin 2A is expressed at high levels in haemopoietic progenitors and down-regulated on differentiation. When it is constitutively expressed in the multipotent haemopoietic cell line, FDCP-Mix, it causes a delay in differentiation and increased clonogenic potential. The serpin is also dramatically up-regulated on T-cell activation. It has an unusual reactive site Cys-Cys sequence, a unique C-terminal extension and lacks a typical cleavable N-terminal signal sequence. In spite of these features, the protein is not a member of the ovalbumin-serpin family, but is instead most closely related to human antichymotrypsin. We have shown that the serpin is intracellular with prominent nuclear localization. Transverse urea gradient gels and CD studies show that the protein undergoes the stressed-relaxed conformational change typical of inhibitory serpins. However, we have not detected complex-forming activity with a set of proteases. Thermal denaturation studies also show that the protein has decreased structural stability under reducing conditions, although it lacks disulphide bonds within the core of the molecule. Our results show that serpin 2A is an intracellular protein with the potential to mediate its biological effects via interaction with non-protease intracellular targets. Furthermore, the results presented suggest a model whereby the serpin interactions could be modulated by redox conditions or conformational change induced by cleavage of the reactive-site loop.
authors.affiliation: Department of Haematology, University College Hospital, Grafton Way, London WC1E 6AU, UK.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Morris
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Dafforn
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Forsyth
authors.forename: Melinda A
authors.initials: MA
authors.lastname: Missen
authors.forename: Anita J
authors.initials: AJ
authors.lastname: Horvath
authors.forename: Lynne
authors.initials: L
authors.lastname: Hampson
authors.forename: Ian N
authors.initials: IN
authors.lastname: Hampson
authors.forename: Graeme
authors.initials: G
authors.lastname: Currie
authors.forename: Robin W
authors.initials: RW
authors.lastname: Carrell
authors.forename: Paul B
authors.initials: PB
authors.lastname: Coughlin
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002942:Circular Dichroism; D003593:Cytoplasm / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D039902:Multipotent Stem Cells / Q000166:cytology / Q000378:metabolism; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015843:Serpins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; C490400:Serpina3k protein, mouse; D015843:Serpins; D010450:Endopeptidases