Table 1.
Chromosome 21 functional gene categories
| Functional categories | Number of genes | Functional assignments |
| Transcription factors, regulators, | 17 | GABPA, BACH1, RUNX1, SIM2, ERG, ETS2 (transcription factors); ZNF294, ZNF295, Pred65, |
| and modulators | *ZNF298, APECED (zinc fingers); KIAA0136 (leucine zipper); GCFC (GC-rich binding protein); | |
| SON (DNA binding domain); PKNOX1 (homeobox); HSF2BP (heat shock transcription factor | ||
| binding protein); NRIP1 (modulator of transcriptional activation by estrogen) | ||
| Chromatin structure | 4 | H2BFS (histone 2B), HMG14 (high mobility group), CHAF1B (chromatin assembly factor), PCNT |
| (pericentrin, an integral component of the pericentriolar matrix of the centrosome) | ||
| Proteases and protease inhibitors | 6 | BACE (beta-site APP cleaving enzyme); TMPRSS2, TMPRSS3 (transmembrane serine proteases); |
| ADAMTS1, ADAMTS5 (metalloproteinases); CSTB (protease inhibitor) | ||
| Ubiquitin pathway | 4 | USP25, USP16 (ubiquitin proteases); UBE2G2 (ubiquitin conjugating enzyme); SMT3A (ubiquitin-like) |
| Interferons and immune response | 9 | IFNAR1, IFNAR2, IL10RB, IFNGR2 (receptors/auxilliary factors); MX1, MX2 (interferon-induced); |
| CCT8 (T-complex subunit), TIAM1 (T-lymphoma invasion and metastasis inducing protein), | ||
| TCP10L (T-complex protein 10 like) | ||
| Kinases | 8 | ENK (enterokinase); MAKV, MNB, KID2 (serine/threonine); PHK (pyridoxal kinase), PFKL |
| (phosphofructokinase); *ANKRD3 (ankyrin-like with kinase domains); PRKCBP2 (protein kinase C | ||
| binding protein) | ||
| Phosphatases | 2 | SYNJ1 (polyphosphinositide phosphatase); PDE9A (cyclicphosphodiesterase) |
| RNA processing | 5 | rA4 (SR protein), U2AF35 (splicing factor), RED1 (editase), PCBP3 (poly(C)-binding protein); |
| *RBM11 (RNA-binding motif) | ||
| Adhesion molecules | 4 | NCAM2 (neural cell), DSCAM; ITGB2 (lymphocyte); c21orf43 (similar to endothelial tight junction |
| molecule) | ||
| Channels | 7 | GRIK1 (glutamate receptor, calcium channel); KCNE1, KCNE2, KNCJ6, KCNJ15 (potassium); |
| *CLIC1l (chloride); TRPC7 (calcium) | ||
| Receptors | 5 | CXADR (Coxsackie and adenovirus); Claudins 8, 14, 17 (Claustridia); Pred12 (mannose) |
| Transporters | 2 | SLC5A3 (Na-myoinositol); ABCG1 (ATP-binding cassette) |
| Energy metabolism | 4 | ATP50 (ATP synthase oligomycin-sensitivity conferral protein); ATP5A (ATPase-coupling factor 6); |
| NDUFV3 (NADH-ubiquinone oxoreductase subunit precursor); CRYZL1 (quinone | ||
| oxidoreductase) | ||
| Structural | 4 | CRYA (lens protein); COL18, COL6A1, COL6A2 (collagens) |
| Methyl transferases | 3 | DNMT3L (cytosine methyl transferase), HRMTIII (protein arginine methyl transferase); Pred28 |
| (AF139682) (N6-DNA methyltransferase) | ||
| SH3 domain | 3 | ITSN, SH3BGR, UBASH3A |
| One carbon metabolism | 4 | GART (purine biosynthesis), CBS (cystathionine-β -synthetase), FTCD (formiminotransferase |
| cyclodeaminase), SLC19A1 (reduced folate carrier) | ||
| Oxygen metabolism | 3 | SOD1 (superoxide dismutase); CBR1, CBR3 (carbonyl reductases) |
| Miscellaneous | 28 | HLCS (holocarboxylase synthase); LSS (lanosterol synthetase); B3GALT5 (galactosyl transferase); |
| *AGPAT3 (acyltransferase); STCH (microsomal stress protein); ANA/BTG3 (cell cycle control); | ||
| MCM3 (DNA replication associated factor); APP (Alzheimer's amyloid precursor); WDR4, WDR9 | ||
| (WD repeat containing proteins); TFF1, 2, 3 (trefoil proteins); UMODL1 (uromodulin); *Pred5 | ||
| (lipase); *Pred3 (keratinocyte growth factor); KIAA0653, *IgSF5 (Ig domain); TMEM1, *Pred44 | ||
| (transmembrane domains); TRPD (tetratricopeptide repeat containing); S100b (Ca binding); PWP2 | ||
| (periodic tryptophan protein); DSCR1 (proline rich); DSCR2 (leucine rich); WRB (tryptophan rich | ||
| protein); Pred22 (tRNA synthetase); SCL37A1 (glycerol phosphate permease) |
In the table, 122 genes are assigned. The majority have complete or presumed complete cDNA sequences. Functional assignments have been based either on literature reports of direct experiment or on inferences from similarities to other proteins. Genes where models are incomplete (*) contain domains that suggest a function. Functional categories were chosen to be broadly descriptive; each gene appears in only one category.