Retinoblastoma Binding Protein 6 (RBBP6) is a 200 KDa protein shown to play a role in 3'- polyadenylation of mRNA transcripts, as well as to function as an E3 ligase catalysing ubiquitination of cancer-associated proteins. RBBP6 has been previously reported to localise to nuclear speckles, which are thought to play a role in mRNA splicing, presumably as a result of its RS domain, which is known to target mRNA splicing factors to nuclear speckles. However recent studies in our laboratory have shown that isoform 3 of RBBP6, consisting mainly of the DWNN domain, also localises to speckles in resting cells, but more strongly in cells subjected to various stresses, suggesting that the DWNN domain may be the speckle-targeting domain. / Magister Scientiae - MSc (Biotechnology)