Protein-interacting V-domains of Aspergillus nidulans PalA/RIM20, Ustilago maydis RIM20, and related proteins
This family belongs to the V_Alix_like superfamily which includes the V-shaped (V) domains of Bro1 and Rim20 from Saccharomyces cerevisiae, mammalian Alix (apoptosis-linked gene-2 interacting protein X), His-Domain type N23 protein tyrosine phosphatase (HD-PTP, also known as PTPN23), and related domains. Aspergillus nidulas PalA/RIM20 and Ustilago maydis RIM20, like Saccharomyces cerevisiae Rim20, participate in the response to the external pH via the Pal/Rim101 pathway; however, Saccharomyces cerevisiae Rim20 does not belong to this family. This pathway is a signaling cascade resulting in the activation of the transcription factor PacC/Rim101. The mammalian Alix V-domain (belonging to a different family) contains a binding site, partially conserved in the superfamily, for the retroviral late assembly (L) domain YPXnL motif. Aspergillus nidulas PalA binds a nonviral YPXnL motif (tandem YPXL/I motifs within PacC). The Alix V-domain is also a dimerization domain. In addition to this V-domain, members of the V_Alix_like superfamily also have an N-terminal Bro1-like domain, which has been shown to bind CHMP4/Snf7, a component of the ESCRT-III complex.
Comment:based on the binding of Alix to the YPXnL (n=1-3) late domains of HIV and EIAV; late domains are short peptide motifs found in viral Gag proteins
Comment:some members of this superfamily have been shown to bind nonviral YPXnL motifs
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