Ikematsu N et al 1999 reported that
Tob2, a novel anti-proliferative Tob/BTG1 family member, associates with a component of the CCR4 transcriptional regulatory complex capable of binding cyclin-dependent kinases.
Human cDNAs encoding a novel member of Tob/BTG1 anti-proliferative family proteins were cloned. The putative protein product termed Tob2 consisted of
344 amino acids with high similarity to the Tob protein, The tob2 mRNA was 4.1
kb long and was ubiquitously expressed in human adult tissues, as was revealed
by Northern blot hybridization, However, further in situ hybridization
analysis showed a characteristic expression of the tob2 mRNA in oocytes,
suggesting a unique role of Tob2 in oogenesis, Like the Tob protein, Tob2
inhibited cell cycle progression from the G0/G1 to S phases. Intriguingly, the
amino-terminal half of Tob2 as well as that of Tob was associated with a human
homologue of yeast Caf1, a component of the CCR4 transcription factor complex,
Moreover, Caf1 was associated with cyclin dependent kinases, These data
suggested that both Tob and Tob2 were involved in cell cycle regulation
through their interaction with Caf1, Finally, the tob2 gene was mapped to
human chromosome 22q13.1-q13.31.
General function
Cell death/survival, Cell cycle regulation
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Oogenesis
Comment
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Tob genes in development and homeostasis. Jia S et al. Members of the Btg/Tob protein family share a conserved N-terminal region that confers the activity to inhibit cell proliferation. Tob1 and Tob2 proteins, which constitute a Tob subfamily, have a longer C-terminal region than BTG proteins. Apparently, genomes of invertebrates and teleost species contain only a single Tob locus, whereas genomes of mammalian, avian, and amphibian species contain two Tob loci (Tob1 and Tob2). Tob genes are expressed in oocytes, sperm, early embryos, and various adult tissues, depending on the species. Recent reports indicate that Tob proteins play important roles in spermatogenesis, embryonic dorsoventral patterning, osteogenesis, T-cell activation, and learning and memory. Accumulating evidence supports the hypothesis that Tob proteins act primarily as transcriptional repressors in several signaling pathways. Developmental Dynamics, 2007. (c) 2007 Wiley-Liss, Inc.