RNA recognition motif (RRM) found in yeast RNA-binding protein PIN4, fission yeast RNA-binding post-transcriptional regulators cip1, cip2 and similar proteins
This subfamily corresponds to the RRM in PIN4, also termed psi inducibility protein 4 or modifier of damage tolerance Mdt1, a novel phosphothreonine (pThr)-containing protein that specifically interacts with the pThr-binding site of the Rad53 FHA1 domain. It is encoded by gene MDT1 (YBL051C) from yeast Saccharomyces cerevisiae. PIN4 is involved in normal G2/M cell cycle progression in the absence of DNA damage and functions as a novel target of checkpoint-dependent cell cycle arrest pathways. It contains an N-terminal RRM, a nuclear localization signal, a coiled coil, and a total of 15 SQ/TQ motifs. cip1 (Csx1-interacting protein 1) and cip2 (Csx1-interacting protein 2) are novel cytoplasmic RRM-containing proteins that counteract Csx1 function during oxidative stress. They are not essential for viability in fission yeast Schizosaccharomyces pombe. Both cip1 and cip2 contain one RRM. Like PIN4, Cip2 also possesses an R3H motif that may function in sequence-specific binding to single-stranded nucleic acids.