In molecular biology, housekeeping genes are typically constitutive genes that are required for the maintenance of basic cellular function, and are expressed in all cells of an organism under normal and patho-physiological conditions. [1] [2] [3] [4] Although some housekeeping genes are expressed at relatively constant rates in most non-pathological situations, the expression of other housekeeping genes may vary depending on experimental conditions. [1] [5]
The origin of the term "housekeeping gene" remains obscure. Literature from 1976 used the term to describe specifically tRNA and rRNA. [6] For experimental purposes, the expression of one or multiple housekeeping genes is used as a reference point for the analysis of expression levels of other genes. The key criterion for the use of a housekeeping gene in this manner is that the chosen housekeeping gene is uniformly expressed with low variance under both control and experimental conditions. Validation of housekeeping genes should be performed before their use in gene expression experiments such as RT-PCR. Recently a web-based database of human and mouse housekeeping genes and reference genes/transcripts, named Housekeeping and Reference Transcript Atlas (HRT Atlas), was developed to offer updated list of housekeeping genes and reliable candidate reference genes/transcripts for RT-qPCR data normalization. [1] This database can be accessed at http://www.housekeeping.unicamp.br.
Housekeeping genes account for majority of the active genes in the genome, and their expression is obviously vital to survival. The housekeeping gene expression levels are fine-tuned to meet the metabolic requirements in various tissues. Biochemical studies on transcription initiation of the housekeeping gene promoters have been difficult, partly due to the less-characterized promoter motifs and transcription initiation process.
Human housekeeping gene promoters are generally depleted of TATA-box, have high GC content and high incidence of CpG Islands. [7] In Drosophila, where promoter specific CpG Islands are absent, housekeeping gene promoters contain DNA elements like DRE, E-box or DPE. [8] Transcription start sites of housekeeping genes can span over a region of around 100 bp whereas transcription start sites of developmentally regulated genes are usually focused in a narrow region. [9] [10] [11] Little is known about how the dispersed transcription initiation of housekeeping gene is established. There are transcription factors that are specifically enriched on and regulate housekeeping gene promoters. [12] [13] Furthermore, housekeeping promoters are regulated by housekeeping enhancers but not developmentally regulated enhancers. [14]
The following is a partial list of "housekeeping genes." For a more complete and updated list, see HRT Atlas database compiled by Bidossessi W. Hounkpe et al. [1] The database was constructed by mining more than 12000 human and mouse RNA-seq datasets. [1]
There is significant overlap in function with regards to some of these proteins. In particular, the Rho-related genes are important in nuclear trafficking (i.e.: mitosis) as well as with mobility along the cytoskeleton in general. These genes of particular interest in cancer research.
(Note that COX1, COX2, and COX3 are mitochondrially encoded)
A specialized form of cell signaling
Although this page is devoted to genes that should be ubiquitously expressed, this section is for genes whose current name reflects their relative upregulation in testes
This is a list of topics in molecular biology. See also index of biochemistry articles.
Chromosome 21 is one of the 23 pairs of chromosomes in humans. Chromosome 21 is both the smallest human autosome and chromosome, with 46.7 million base pairs representing about 1.5 percent of the total DNA in cells. Most people have two copies of chromosome 21, while those with three copies of chromosome 21 have Down syndrome.
Chromosome 1 is the designation for the largest human chromosome. Humans have two copies of chromosome 1, as they do with all of the autosomes, which are the non-sex chromosomes. Chromosome 1 spans about 249 million nucleotide base pairs, which are the basic units of information for DNA. It represents about 8% of the total DNA in human cells.
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans nearly 171 million base pairs and represents between 5.5 and 6% of the total DNA in cells. It contains the major histocompatibility complex, which contains over 100 genes related to the immune response, and plays a vital role in organ transplantation.
Chromosome 13 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 13 spans about 113 million base pairs and represents between 3.5 and 4% of the total DNA in cells.
Chromosome 2 is one of the twenty-three pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second-largest human chromosome, spanning more than 242 million base pairs and representing almost eight percent of the total DNA in human cells.
Chromosome 3 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 3 spans more than 198 million base pairs and represents about 6.5 percent of the total DNA in cells.
Chromosome 4 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 4 spans more than 190 million base pairs and represents between 6 and 6.5 percent of the total DNA in cells.
Chromosome 8 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 8 spans about 146 million base pairs and represents between 4.5 and 5.0% of the total DNA in cells.
Chromosome 9 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome, as they normally do with all chromosomes. Chromosome 9 spans about 138 million base pairs of nucleic acids and represents between 4.0 and 4.5% of the total DNA in cells.
Chromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 133 million base pairs and represents between 4 and 4.5 percent of the total DNA in cells.
Chromosome 16 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 16 spans about 90 million base pairs and represents just under 3% of the total DNA in cells.
Chromosome 19 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 19 spans more than 61.7 million base pairs, the building material of DNA. It is considered the most gene-rich chromosome containing roughly 1,500 genes, despite accounting for only 2 percent of the human genome.
Ribosome biogenesis is the process of making ribosomes. In prokaryotes, this process takes place in the cytoplasm with the transcription of many ribosome gene operons. In eukaryotes, it takes place both in the cytoplasm and in the nucleolus. It involves the coordinated function of over 200 proteins in the synthesis and processing of the three prokaryotic or four eukaryotic rRNAs, as well as assembly of those rRNAs with the ribosomal proteins. Most of the ribosomal proteins fall into various energy-consuming enzyme families including ATP-dependent RNA helicases, AAA-ATPases, GTPases, and kinases. About 60% of a cell's energy is spent on ribosome production and maintenance.
26S protease regulatory subunit 6A, also known as 26S proteasome AAA-ATPase subunit Rpt5, is an enzyme that in humans is encoded by the PSMC3 gene. This protein is one of the 19 essential subunits of a complete assembled 19S proteasome complex Six 26S proteasome AAA-ATPase subunits together with four non-ATPase subunits form the base sub complex of 19S regulatory particle for proteasome complex.
26S proteasome non-ATPase regulatory subunit 13 is an enzyme that in humans is encoded by the PSMD13 gene.
26S protease regulatory subunit 8, also known as 26S proteasome AAA-ATPase subunit Rpt6, is an enzyme that in humans is encoded by the PSMC5 gene. This protein is one of the 19 essential subunits of a complete assembled 19S proteasome complex Six 26S proteasome AAA-ATPase subunits together with four non-ATPase subunits form the base sub complex of 19S regulatory particle for proteasome complex.
26S protease regulatory subunit 7, also known as 26S proteasome AAA-ATPase subunit Rpt1, is an enzyme that in humans is encoded by the PSMC2 gene This protein is one of the 19 essential subunits of a complete assembled 19S proteasome complex. Six 26S proteasome AAA-ATPase subunits together with four non-ATPase subunits form the base sub complex of 19S regulatory particle for proteasome complex.
26S proteasome non-ATPase regulatory subunit 11 is an enzyme that in humans is encoded by the PSMD11 gene.
From Hounkpe BW, Chenou F; de Lima F; De Paula E Nucleic Acids Research
From Eisenberg E, Levanon EY; Trends in Genetics 19, 362–365 (2003)
From Eisenberg E, Levanon EY; Trends in Genetics, 29 (2013)