Human Ccr4-Not complexes contain variable deadenylase subunits

• Published in: Biochemical journal Vol. 422; no. 3; p. 443
• Main Authors: Lau, Nga-Chi, Kolkman, Annemieke, van Schaik, Frederik M A, Mulder, Klaas W, Pijnappel, W W M Pim, Heck, Albert J R, Timmers, H Th Marc
• Format: Journal Article
• Language: English
• Published: England 15-09-2009
• Subjects: Biological Transport; Cell Line; Chromatography, Gel; Computational Biology; Exoribonucleases - genetics; Exoribonucleases - metabolism; HeLa Cells; Humans; Protein Binding; Proteomics; Repressor Proteins - chemistry; Repressor Proteins - metabolism; RNA Splicing - genetics; RNA Splicing - physiology; Tandem Mass Spectrometry; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Two-Hybrid System Techniques
• ISSN: 1470-8728
• DOI: 10.1042/BJ20090500

The Ccr4-Not complex is evolutionarily conserved and important for regulation of mRNA synthesis and decay. The composition of the yeast complex has been well described. Orthologues of the yeast Ccr4-Not components have been identified in human cells including multiple subunits with mRNA deadenylase activity. In the present study, we examine the composition of the human Ccr4-Not complex in an in-depth proteomic approach using stable cell lines expressing tagged CNOT proteins. We find at least four different variants of the human complex, consisting of seven stable core proteins and mutually exclusive associated mRNA deadenylase subunits. Interestingly, human CNOT4 is in a separate approximately 200 kDa complex. Furthermore, analyses of associated proteins indicate involvement of Ccr4-Not complexes in splicing, transport and localization of RNA molecules. Taken together, human Ccr4-Not complexes are heterogeneous in composition owing to differences in their deadenylase subunits, which may reflect the multi-functionality of these complexes in cellular processes.