Target type: cellularcomponent
A protein complex that possesses beta-galactosidase activity, i.e. catalyzes the hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides. In E. coli, the complex is a homotetramer; dimeric and hexameric beta-galactosidase complexes have been observed in other species. [PMID:15950161]
The beta-galactosidase complex is a multimeric protein complex that catalyzes the hydrolysis of lactose into glucose and galactose. The cellular component of this complex is primarily located in the cytoplasm of bacterial cells, but it can also be found in the periplasmic space. The complex is composed of four identical subunits, each of which contains a catalytic domain and a lactose-binding domain. The catalytic domain is responsible for cleaving the glycosidic bond between glucose and galactose in lactose, while the lactose-binding domain is responsible for binding lactose to the enzyme. The four subunits assemble into a tetrameric structure, with each subunit interacting with its two neighbors. This tetrameric structure is essential for the proper functioning of the enzyme, as it provides a stable platform for the catalytic domains to work together. In addition to the four subunits, the beta-galactosidase complex may also contain other proteins, such as chaperones, that help to stabilize the complex and ensure its proper folding. The cellular localization of the beta-galactosidase complex is critical for its function. By being located in the cytoplasm, the enzyme is able to access lactose, which is transported into the cell from the external environment. The location of the complex in the cytoplasm also allows it to interact with other enzymes involved in lactose metabolism. The beta-galactosidase complex is a highly regulated enzyme, and its activity is controlled by a variety of factors, including the availability of lactose and the concentration of intracellular cAMP. This regulation ensures that the enzyme is only active when it is needed, which helps to conserve cellular resources.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Beta-galactosidase | A bacterial-type beta-galactosidase that is encoded in the genome of Escherichia coli K-12. [PRO:DAN, UniProtKB:P00722] | Escherichia coli K-12 |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| 1,4-dideoxy-1,4-iminoarabinitol | 1,4-dideoxy-1,4-iminoarabinitol: RN given refers to (2S-(2alpha,3beta,4alpha))-isomer; structure given in first source | ||
| isopropyl thiogalactoside | isopropyl beta-D-thiogalactopyranoside : An S-glycosyl compound consisting of beta-D-1-thiogalactose having an isopropyl group attached to the anomeric sulfur. Isopropyl Thiogalactoside: A non-metabolizable galactose analog that induces expression of the LAC OPERON. | S-glycosyl compound |