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Protein numb homolog is a protein that in humans is encoded by the ''NUMB'' gene. The protein encoded by this gene plays a role in the determination of cell fates during development. The encoded protein, whose degradation is induced in a proteasome-dependent manner by MDM2, is a membrane-bound protein that has been shown to associate with EPS15, LNX1, and NOTCH1. Four transcript variants encoding different isoforms have been found for this gene.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=8650 )〕 The protein Numb is coded for by the gene, ''NUMB'', whose mechanism appears to be evolutionarily conserved. Numb has been extensively studied in both invertebrates and mammals, though its function is best understood in ''Drosophila''. Numb plays a crucial role in asymmetrical cell division during development, allowing for differential cell fate specification in the central and peripheral nervous systems. During neurogenesis, Numb localizes to one side of the mother cell such that it is distributed selectively to one daughter cell. This asymmetric division allows a daughter cell containing Numb to acquire a different fate than the other daughter cell. == Gene == The numb gene protein product controls binary cell fate decisions in the peripheral and central nervous systems of both invertebrates and mammals during neurogenesis. During cell division, Numb is asymmetrically localized to one end of the progenitor cell and subsequently segregates to only one daughter cell where it intrinsically determines cell fate.〔 Numb protein signaling plays a key role in binary cell fate decisions following asymmetric cell divisions. One daughter cell, generally that receiving the Numb, is able to adopt a neuronal fate and innervate the developing nervous system. The other daughter cell becomes a progenitor cell to fill the lost role of the parent cell and maintain proliferation. In addition to its role in proliferation and differentiation, Numb has also been shown to play a role in tumorigenesis and the response of neural progenitors to chemotactic cues during migration. In mammals, there are four alternatively spliced forms of the Numb protein. In addition, there is a Numb homolog called “Numb-like,” or NUMBL. Numb proteins in mammals are not as well understood as their fly counterparts. The various forms of Numb have differential progenitor-promoting and differentiation-promoting functions. More research is necessary to understand the complex relationships between these forms of Numb and their functions. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NUMB (gene)」の詳細全文を読む スポンサード リンク
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