Transmembrane protein 132B is a protein encoding gene that encodes the human TMEM132B protein. Variant 1 of human TMEM132B consists of 1078 amino acids.[5]
Gene
The TMEM132B gene is located on chromosome 12 at 12q24.31 and contains 18 exons.[6][7] In humans, exons 1-9 include the coding region and exons 10-18 include only 3' untranslated region (UTR). TMEM132B primarily localizes in the cytoplasm.
Expression
Human TMEM132B is expressed in the brain as well as the fetal brain. Small amounts of TMEM132B have been found in the thyroid, salivary gland, prostate, intestinal organs, and the placenta.[8]
TMEM132B is expressed under various conditions, most of which occur in the brain. One example of TMEM132B expression in the brain is seen in Parkinson’s disease, particularly in the substantia nigra. The substantia nigra is located in the basal ganglia of the brain and is essential for controlling body movements.[9] Microarray data[10] suggests that individuals with Parkinson’s disease have moderate to low TMEM132B expression (68%–75%) compared to those without Parkinson’s disease (75%–91%).
Protein
The human TMEM132B gene encodes a protein of 1078 amnio acids in length. Human TMEME132B has one transmembrane region and three N-glycosylation sites.[8] TMEM132B has a predicted molecular weight of 119.5 kD and a predicted isoelectric point (pI) of 5.[11]
Tertiary structure for TMEM132B according to AlphaFold[12].Schematic of Human TMEM132B. Yellow circles indicate phosphorylation sites, pink triangles indicate sulfonation sites, and cyan squares indicate glycosylation sites.
Interacting Proteins
TMEM132B has different proteins that interact with it. There are four main proteins that were found to have interactions with TMEM132B. Of the four that were found, two are located in the cytoplasm, one is in the cytosol, and one is in the postsynaptic membrane (see table 1).
Table 1. Proteins that interact with TMEM132B and their function.
Protein folding enzyme. Important in protein folding and catalyzing certain peptide bonds.
Cross-Linking-MS (XL-MS)
Cytosol. It can be secreted to extracellular regions
Evolution
Orthologs
Ortholog sequences for TMEM132B were found in primates, mammals, reptiles, birds, and amphibians. Amphibians were the last taxon group found that contained TMEM132B. Ortholog sequences were organized by median date of divergence with the farthest date of divergence being 352 MYA. See Table 2.
TMEM132B has a lot of paralogs in humans. The main paralogs were TMEM132A, TMEM132C, TMEM132D, and TMEM132E. These four paralogs are what make up the human TMEM132 family.
