Alternative titles; symbols
HGNC Approved Gene Symbol: IMP3
Cytogenetic location: 15q24.2 Genomic coordinates (GRCh38) : 15:75,639,093-75,640,224 (from NCBI)
IMP3 forms a ternary complex with IMP4 (612981) and MPP10 (MPHOSPH10; 605503) that interacts with U3 small nucleolar RNA (snoRNA), which is required for the early cleavage steps in pre-rRNA processing (Granneman et al., 2003).
By database analysis using yeast Imp3 cDNA-based oligonucleotides, followed by PCR of a teratocarcinoma cDNA library, Granneman et al. (2003) cloned human IMP3. The deduced 180-amino acid protein has a calculated molecular mass of 21.8 kD and shares approximately 50% identity with yeast Imp3. IMP3 contains a predicted coiled-coil domain and an S4 domain. Fluorescence microscopy localized IMP3 to the nucleoli in transfected Hep2 cells.
By coimmunoprecipitation and Northern blot analysis, Granneman et al. (2003) demonstrated that IMP3 interacts with the U3 snoRNA complex. They showed that mouse Imp3 partially complemented the mutant phenotype of the Imp3-null allele in yeast at 22 degrees. Glycerol gradient cosedimentation and GST pull-down studies showed that IMP3, IMP4, and MPP10 form a heterotrimeric protein complex. Analysis of deletion mutants showed that both the IMP3 S4 domain and coiled-coil region are required for interaction with MPP10 amino acids 457 to 565. Granneman et al. (2003) determined that complex formation is required for nucleolar localization of these proteins, with sequences of MPP10 directing nucleolar import and nuclear localization of the heterotrimeric complex.
Granneman, S., Gallagher, J. E. G., Vogelzangs, J., Horstman, W., van Venrooij, W. J., Baserga, S. J., Pruijn, G. J. M. The human Imp3 and Imp4 proteins form a ternary complex with hMpp10, which only interacts with the U3 snoRNA in 60-80S ribonucleoprotein complexes. Nucleic Acids Res. 31: 1877-1887, 2003. [PubMed: 12655004] [Full Text: https://doi.org/10.1093/nar/gkg300]