= TMEM238 =Transmembrane protein 238 is a transmembrane protein that in humans is encoded by the TMEM238 gene.[1] The Homo sapiens TMEM238 gene is related to Bardet-Biedl Syndrome 2 and may play a role in amino acid transport.[2]
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TMEM238 in Homo sapiens spans 5,049 base pairs and has two exons. TMEM238 is located near the end of the long arm of chromosome 19 in humans.[3] More specifically, it's located at 19q13.42 on the minus strand of the chromosome. No splice isoforms or variants are known.
TMEM238 is chromosomally located between the transmembrane protein 190 (TMEM190) gene and ribosomal protein L28 (RPL28) gene.[4] TMEM190 is involved in protein self-association and hematopoietic progenitor cell differentiation. RPL28 encodes a ribosomal protein that is part of the large 60S subunit.
Accession numbers: NM_001190764.2 (mRNA), NP_001177693.1(protein).
Transmembrane protein 238 is composed of 176 amino acids, weighing approximately ~18.0 kDa. It has a basal isoelectric point of ~11.5.[5] The protein is rich in alanine, arginine, and small amino acids, with a greater preponderance of basic amino acids. The protein is predicted to be an integral component of the cell membrane, containing two transmembrane domains.
The secondary structure of the protein has two transmembrane domains shown as dark blue alpha helices.
Protein topology within the membrane shows extracellular N- and C-terminals with a short intracellular domain between transmembrane domains.
TMEM238 shows higher expression in colon and stomach tissues, but variable ubiquitous expression in all other tissues. TMEM238 gene expression in the mouse brain shows higher expression in the pons and medulla as indicated by white arrows in the sagittal plane view.[6]
The presence of two transmembrane domains within the protein confirm its presence in the plasma membrane.[7]
The protein is not glycosylphosphatidylinositol (GPI) anchored, instead relying on hydrophobic transmembrane domains.[8]
Seven post-translational phosphorylation modification sites were found within the protein, one existing within one of the transmembrane regions.[9] ,[10] ,[11]
Orthologs can be found in most vertebrates including mammals, birds, reptiles, amphibians, and fishes, but not in any invertebrates.
| Mammalia | Homo sapiens | Human | 0 | NP_001177693.1 | 176 | 100.0 | 100.0 | |
| Mammalia | Mus musculus | Rodentia | 87 | NP_083660.1 | 176 | 85.2 | 86.9 | |
| Mammalia | Eschrichtius robustus | Gray Whale | 94 | XP_068384946.1 | 178 | 87.1 | 91.0 | |
| Mammalia | Trichosurus vulpecula | Common Brushtail Possum | 160 | XP_036599039.1 | 168 | 65.8 | 70.7 | |
| Reptilia | Alligator mississippiensis | American Alligator | 319 | XP_019356415.1 | 131 | 48.9 | 55.0 | |
| Reptilia | Malaclemys terrapin pileata | Mississippi Diamondback Terrapin Turtle | 319 | XP_053865811.1 | 123 | 43.2 | 54.0 | |
| Reptilia | Pantherophis guttatus | Corn Snake | 319 | XP_034292043.1 | 158 | 33.0 | 42.0 | |
| Aves | Gallus gallus | Red Junglefowl Chicken | 319 | XP_040503607.1 | 135 | 33.3 | 41.4 | |
| Aves | Sylvia atricapilla | Eurasian Blackcap Bird | 319 | XP_066185702.1 | 131 | 33.0 | 39.5 | |
| Amphibia | Xenopus laevis | African Clawed Frog | 352 | XP_018083581.1 | 160 | 39.7 | 51.3 | |
| Amphibia | Bufotes viridis | European Green Toad | 352 | CAK8623525.1 | 137 | 36.5 | 48.6 | |
| Dipnoi | Protopterus annectens | West African Lungfish | 408 | XP_043937488.1 | 138 | 36.4 | 50.0 | |
| Coelacanthi | Latimeria chalumnae | West Indian Ocean Coelacanth | 415 | XP_006010124.1 | 143 | 41.1 | 53.3 | |
| Ray-Finned Fishes | Nothobranchius furzeri | Turquoise Killifish | 429 | XP_015830691.2 | 104 | 29.0 | 40.3 | |
| Ray-Finned Fishes | Danio rerio | Zebrafish | 429 | NP_001076543.1 | 105 | 26.4 | 37.4 | |
| Ray-Finned Fishes | Nerophis ophidion | Straightnose Pipefish | 429 | XP_061764902.1 | 191 | 26.1 | 42.4 | |
| Ray-Finned Fishes | Hippocampus zosterae | Dwarf Seahorse | 429 | XP_051927990.1 | 185 | 25.6 | 33.8 | |
| Cartilaginous Fishes | Callorhinchus milii | Australian Ghostshark | 462 | XP_007905786.1 | 144 | 38.8 | 52.5 | |
| Cartilaginous Fishes | Chiloscyllium plagiosum | Whitespotted Bamboo Shark | 462 | XP_043571155.1 | 155 | 27.2 | 37.6 | |
| Hyperoartia | Lethenteron reissneri | Asiatic Brook Lamprey | 563 | XP_061425829.1 | 210 | 27.3 | 34.3 | |
| Hyperoartia | Petromyzon marinus | Sea Lamprey | 563 | XP_032832039.1 | 158 | 25.3 | 38.7 |
TMEM238 is evolving moderately quickly in history with a rate faster than cytochrome c but slower than fibrinogen alpha.[12]
The TMEM238 protein is predicted to be an integral component of the membrane and play a role in amino acid transport.[13]
| HNRNPH1 | Heterogeneous Nuclear Ribonucleoprotein H1 | >0.400 | Nucleus, Cytoplasm | RNA binding protein, pre-mRNA processing | |
| KRTCAP3 | Keratinocyte Associated Protein 3 | 0.4504 | Cell Membrane | Adiposity | |
| TMEM30B | Transmembrane Protein 30B | 0.4512 | Cell Membrane, Golgi, ER | Aminophospholipid transport, regulate protein exit from ER | |
| TMEM223 | Transmembrane Protein 223 | 0.524 | Cell Membrane | Nervous System Development | |
| CATSPERB | Cation Channel Sperm-Associated Protein Subunit Beta | 0.573 | Cell Membrane, Cilium | Sperm cell hyperactivation, motility, spermatogenesis |
The Homo sapiens TMEM238 gene is related to Bardet-Biedl Syndrome 2, a ciliopathic human genetic disorder.
Expression of the TMEM238 gene was also shown to increase in several disease states including asthma and low invasive breast cancers as found in various microarray experiments.[14] ,[15]