High impact information on SIK1

• Here we report that Nop56p, a protein related in sequence to Nop58p, is a bona fide box C+D snoRNP component; all tested box C+D snoRNAs were coprecipitated with protein A-tagged Nop56p [1].
• Analysis of in vivo snoRNP assembly indicated that Nop56p was stably associated with the snoRNAs only in the presence of Nop1p [1].
• In addition, SIK1 fails to partition the apical cell; thus, nuclei are not likely to arrest mitosis in interphase as in normal cells, but continue to divide, accumulating to high levels [2].
• We found that over-expression of HXT11 (which encodes a plasma membrane transporter), PPE1 (coding for a protein methyl esterase), or SIK1 (which encodes a protein involved in rRNA processing) shortened the duration of the G1 phase of the cell cycle, prior to the initiation of DNA replication [3].
• Mapping the 5' end of X. laevis Nop56 transcript indicates that it starts with a pyrimidine tract and the analysis of genomic clones revealed a snoRNA encoded in one of NOP56 introns [4].

Biological context of SIK1

• Nop5p shows significant sequence homology with yeast Sik1p/Nop56p, and putative homologues in archaebacteria, plants, and human [5].
• MARBP-1 and MARBP-2 are homologous to yeast nucleolar proteins Nop56p and Nop58p, which are involved in ribosome biogenesis, and to similar highly conserved proteins in other eukaryotes and in archaebacteria [6].

Associations of SIK1 with chemical compounds

• Drosophila Nop56p proteins contain lysine-rich regions at their carboxy-terminus, and show a high degree of similarity to other Nop56p proteins from different organisms [7].

References