title: Charge heterogeneity of macrophage migration inhibitory factor (MIF) in human liver and breast tissue.
abstract: Macrophage migration inhibitory factor (MIF) is an ubiquitous protein playing various immunological and hormonal roles. Theoretical electrophoretic coordinates calculated from protein sequence in the SWISS-PROT database (AC P14174) are 12 kDa and pI 8.24. Using two-dimensional (2-D) immunoblotting, we have detected isoelectric forms at ca. 11.9 kDa, with pI values of 7.8 and 6.98 in human liver tissue, breast tissue and a cell line and in preparations of human MIF expressed in E. coli. This evidence suggests that MIF charge heterogeneity originates from a post-translational modification not requiring eukaryote-specific enzymes. We have also detected in human liver a minor immunoreactive spot at pI 6.23, which coincides with the MIF spot in the liver map in SWISS-2DPAGE. The pI 6.23 isoform also conceivably derives from post-translational modification, as MIF is known to be encoded in the human genome by a single copy gene.
authors.affiliation: Dipartimento di Biologia Molecolare, Università degli Studi di Siena, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Magi
authors.forename: L
authors.initials: L
authors.lastname: Bini
authors.forename: S
authors.initials: S
authors.lastname: Liberatori
authors.forename: B
authors.initials: B
authors.lastname: Marzocchi
authors.forename: R
authors.initials: R
authors.lastname: Raggiaschi
authors.forename: F
authors.initials: F
authors.lastname: Arcuri
authors.forename: S A
authors.initials: SA
authors.lastname: Tripodi
authors.forename: M
authors.initials: M
authors.lastname: Cintorino
authors.forename: P
authors.initials: P
authors.lastname: Tosi
authors.forename: V
authors.initials: V
authors.lastname: Pallini
mesh_terms: D000595:Amino Acid Sequence; D001940:Breast / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D007526:Isoelectric Point; D008099:Liver / Q000737:chemistry*; D008263:Macrophage Migration-Inhibitory Factors / Q000032:analysis / Q000737:chemistry*; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D014407:Tumor Cells, Cultured
chemical_list: D008263:Macrophage Migration-Inhibitory Factors