Table 1. Summary of background binding proteins.
| Biological process | Cellular component | Total no. of peptides | Remarks |
|---|---|---|---|
| Metabolism | Mitochondrion | >180 | Carboxylases, acyltransferases, etc. |
| mRNA processing | Nucleus | 120 | Splicing factors, hnRNPs, ATP-dependent RNA helicases, etc. |
| Protein biosynthesis | Cytosol | 93 | Ribosomal proteins, etc. |
| Receptor activity? | Unknown | 17 | Single protein: thyroid hormone receptor-associated protein |
| RNA processing? | Unknown | 16 | Four proteins with RNA-binding motifs |
| Cytoskeleton | 13 | Actin, lamin | |
| Chromatin assembly | Nucleosome | 13 | Histones |
| Apoptotic program | Nucleolus | 10 | Single protein: apoptotic chromatin condensation inducer in the nucleus |
| No information | Unknown | 10 | Bcl-2-associated transcription factor |
| Ribosome biogenesis | Nucleolus | 9 | SnoRNA-binding proteins, fibrillarin |
| Protein targeting | Nucleus | 5 | Single protein: cdc5-like |
| Electron transport | Microsomes | 5 | Single protein: oxidoreductase |
| No information | Nucleolar | 4 | myb-binding protein 1a |
| Chromatin | Nucleus | 3 | Single protein: SAP 18 |
| Modification | |||
| DNA recombination | Nucleus | 2 | Two proteins: pontin and reptin (RuvB-like) |
| Transcription regulation | Nucleus | 2 | Two proteins: Y box transcription factor 1 (1 peptide); thymocyte selection associated HMG box (1 peptide) |
| Total no. of peptides | >500 | ||
| Gel slices | ∼21 | ||
| Protein molecular mass range, kDa | 15-274 |
Proteins identified by MS were classified according to biological function and cellular localization, with the criteria used by the Gene Ontology Consortium. Also shown is the number of peptides identified for each class of proteins.