Cloning of murine low molecular weight phosphotyrosine protein phosphatase cDNA: identification of a new isoform.
The low molecular weight phosphotyrosine protein phosphatase (LMW-PTP) is a 18 kDa cytosolic enzyme, involved in the negative regulation of cell proliferation. In different mammalian species LMW-PTPs are expressed in two molecular forms produced from a single primary transcript through an alternative splicing mechanism. In this paper we report the cloning, expression and characterization of mouse isoforms of LMW-PTPs (called m-IF1 and m-IF2), very similar to the corresponding rat and human isoenzymes. Moreover we have identified a third cDNA encoding a protein (m-IF2P) that presents three substitutions compared to m-IF2. This new isoform is still active on pNPP, although to a lower extent: this reduction is mainly due to the leucine to proline substitution in position 13, within the catalytic loop. The mRNA expression level of this isoform is comparable to those of m-IF1 and m-IF2. It is likely that a gene duplication process followed by mutations has generated this new gene.
Magherini
F
F
Dipartimento di Scienze Biochimiche, Università di Firenze, Florence, Italy.
Giannoni
E
E
Raugei
G
G
Cirri
P
P
Paoli
P
P
Modesti
A
A
Camici
G
G
Ramponi
G
G
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis
D018076:DNA, Complementary; D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D017027:Protein Tyrosine Phosphatases