RING finger, H2 subclass, found in E3 ubiquitin-protein ligase Deltex1 (DTX1), Deltex2 (DTX2), Deltex4 (DTX4), and similar proteins
This subfamily contains the vertebrate homologs of Drosophila melanogaster Deltex, specifically DTX1, DTX2, and DTX4, and other similar proteins mainly from eumetazoa. The vertebrate homologs of Deltex are involved in Notch signaling and neurogenesis. Mammalian DTX1 is most closely related to the Drosophila Deltex. Both of them bind to SH3-domain containing protein Grb2 and further inhibit E2A. DTX1 functions as a Notch downstream transcription regulator. It interacts with the transcription coactivator p300 and inhibits transcription activation mediated by the neural specific transcription factor MASH1. It is also a transcription target of nuclear factor of activated T cells (NFAT) and participates in T cell anergy and Foxp3 protein level maintenance in vivo. Moreover, DTX1 promotes protein kinase C theta degradation and sustains Casitas B-lineage lymphoma expression. DTX4, also known as RING finger protein 155, shares the highest degree of sequence similarity with DTX1. So it likely interacts with the intracellular domain of Notch as well. Like DTX1 and DTX4, DTX2 is expressed in thymocytes. It interacts with the intracellular domain of Notch receptors and acts as a negative regulator of Notch signals in T cells. However, the endogenous levels of DTX1 and DTX2 is not important for regulating Notch signals during thymocyte development. In contrast to other DTXs, DTX3 does not contain two Notch-binding WWE domains at the N-terminus, but rather a short unique N-terminal domain. It does not interact with the intracellular domain of Notch. In addition, it has a different class of RING finger (C3HC4 type or RING-HC subclass), compared with the other DTXs which harbor a C3H2C3-type RING-H2 finger. Thus DTX3 is not included in this subfamily. Drosophila melanogaster Deltex also does not belong to this subfamily.
Structure:1V87; Mus musculus Deltex2 binding two Zn2+ ions through its RING-H2 finger.
Comment:C3H2C3-type RING-H2 finger consensus motif: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-H-X2-C-X(4-48)-C-X2-C, where X is any amino acid and the number of X residues varies in different fingers
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
Jiyao W et al.(2023). "The conserved domain database in 2023.",