The key difference between housekeeping genes and luxury genes is that housekeeping genes are always expressed in all cells at a constant rate, while luxury genes are expressed only in certain types of cells.
Gene is the unit of heredity. It is a specific sequence of DNA that codes for a protein. A gene should be expressed in order to produce its protein product. It happens via two steps: transcription and translation. There are different types of genes based on function and activity. Housekeeping genes and luxury genes are two types of genes. Housekeeping genes are expressed continuously in all cell types. In contrast, luxury genes are expressed in some types of cells as per the requirement.
CONTENTS
1. Overview and Key Difference
2. What are Housekeeping Genes
3. What are Luxury Genes
4. Similarities Between Housekeeping Genes and Luxury Genes
5. Side by Side Comparison – Housekeeping Genes vs Luxury Genes in Tabular Form
6. Summary
What are Housekeeping Genes?
Housekeeping genes or constitutive genes are the genes expressed continuously in all cells. These genes produce their protein products in an ongoing manner without regulation. These genes are mainly involved in processes vital for cell function and survival of organisms. Basic cell maintenance processes mainly depend on the housekeeping gene products. Hence, these genes maintain constant expression levels in all cells. Glycolysis, citric acid cycle, transcription and translation are some of the processes occurring continuously in cells. The enzymes involved in these processes are continuously synthesizing, and the genes that code for these enzymes are housekeeping genes. They always remain ‘on’ state.
What are Luxury Genes?
Luxury genes, also known as non-constitutive genes or specialists genes, are the genes expressed in certain cells when there is a need for their products. Therefore, luxury genes are not always expressed in a cell. They remain inactive most of the time. But, when their products are needed, they express themselves in certain cells. Serum albumin gene is a luxury gene expressed only in liver cells. Insulin gene is another luxury gene expressed only in pancreatic beta cells. These genes become ‘on’ or ‘off’ according to the requirement.
Figure 01: Luxury Genes
Nitrate reductase genes in plants and lactose system in E. coli are also luxury genes. Genes coding for heat shock proteins are luxury genes, as well. These genes code for specialized protein products. Their expression is regulated.
What are the Similarities Between Housekeeping Genes and Luxury Genes?
- Housekeeping genes and luxury genes are two types of genes based on the function.
- They express and produce proteins.
- They undergo transcription and translation.
- Both types of genes are extremely important for living organisms.
What is the Difference Between Housekeeping Genes and Luxury Genes?
Housekeeping genes are the genes that are constitutively expressed at a relatively constant rate in all cells. In contrast, luxury genes are the genes that are not constantly expressed in cells. They are tissue or organ-specific genes which express themselves only when their products are needed. So, this is the key difference between housekeeping genes and luxury genes. Housekeeping genes code for proteins that are constantly required by the cell while luxury genes code for specialized proteins required by certain cells at certain times.
The below info-graphic tabulates the differences between housekeeping genes and luxury genes in more detail.
Summary – Housekeeping Genes vs Luxury Genes
Genes are classified based on function and activity. Housekeeping genes are the genes expressed in all cells at a constant rate. These genes produce proteins that are essential for the basic activities of cells. Luxury genes are the genes not always expressed themselves in cells. They are only expressed in certain cells as per the requirement. Therefore, they are tissue-specific or organ-specific genes. The key difference between housekeeping genes and luxury genes depends on the expression. Housekeeping genes are constantly expressed, while luxury genes are not constantly expressed. Moreover, the expression of housekeeping genes is not regulated while the expression of luxury genes is highly regulated.
Reference:
1. “Genes Types: Top 17 Types Of Genes (With Role And Activity)”. Biology Discussion, 2020, Available here.
2. More, Hemant. “Types of Genes: Housekeeping Genes, Luxury Genes, Structural Genes, Etc.” The Fact Factor, 13 Mar. 2020, Available here.
Image Courtesy:
1. “Lac-operon” By Barbarossa at Dutch Wikipedia (CC BY-SA 3.0) via Commons Wikimedia