TULA Proteins in Men, Mice, Hens, and Lice: Welcome to the Family

The two members of the UBASH3/STS/TULA protein family have been shown to critically regulate key biological functions, including immunity and hemostasis, in mammalian biological systems. Negative regulation of signaling through immune receptor tyrosine-based activation motif (ITAM)- and hemITAM-bearing receptors mediated by Syk-family protein tyrosine kinases appears to be a major molecular mechanism of the down-regulatory effect of TULA-family proteins, which possess protein tyrosine phosphatase (PTP) activity. However, these proteins are likely to carry out some PTP-independent functions as well. Whereas the effects of TULA-family proteins overlap, their characteristics and their individual contributions to cellular regulation also demonstrate clearly distinct features. Protein structure, enzymatic activity, molecular mechanisms of regulation, and biological functions of TULA-family proteins are discussed in this review. In particular, the usefulness of the comparative analysis of TULA proteins in various metazoan taxa, for identifying potential roles of TULA-family proteins outside of their functions already established in mammalian systems, is examined.

Automated summary

The UBASH3/STS/TULA protein family plays critical roles in regulating key biological functions, such as immunity and hemostasis, in mammalian systems. The TULA-family proteins negatively regulate signaling through immune receptor tyrosine-based activation motif (ITAM)- and hemITAM-bearing receptors, mainly through their protein tyrosine phosphatase (PTP) activity. However, they may also carry out PTP-independent functions. This review discusses the protein structure, enzymatic activity, molecular regulation mechanisms, and biological functions of TULA-family proteins, and examines the comparative analysis of TULA proteins in different metazoan taxa to identify potential roles outside of mammalian systems.