LSMEM2
Leucine rich single-pass membrane protein 2 is a single-pass membrane protein rich in leucine, that in humans is encoded by the LSMEM2 gene. The LSMEM2 protein is conserved in mammals, birds, and reptiles. In humans, LSMEM2 is found to be highly expressed in the heart, skeletal muscle and tongue.
Gene
LSMEM2 is also known as c3orf45. It is found at human chromosome loci 3p21 on the plus strand from bases 50,277,907-50,288,116. This gene is 1,434 base pairs long and has four exon regions. Nearby genes include SEMA3B and IFRD2.mRNA
LSMEM2 has two different isoforms, isoform 1 and 2. These two isoforms encode the same protein. Isoform 2 uses an alternate in-frame splice-site in the 5' coding region in comparison to isoform 1. Isoform 1 is three base pairs and one amino acid longer than isoform 2 at the exon 2 and exon 3 junction.Protein
The LSMEM2 protein has two isoforms. Isoform 1 has an alanine added after amino acid 57, otherwise the two isoforms are identical. It has a predicted MW of 17.8 kDa and isoelectric point of 5.7 pI. LSMEM2 is predicted to have one transmembrane region which is composed of 50% leucine and considered leucine rich. The N-terminus is predicted to be the cytosolic/intracellular region of the protein, while the C-terminus is predicted as the lumenal/extracellular region. It is found to have one domain, Domain of unknown function 4714, spanning from amino acid 13 to 161.Post-translational Modifications
LSMEM2 is predicted to have an acetylation and palmitoylation site near the N-terminus of the protein. It is also predicted to have various phosphorylation and O-GlcNAc sites throughout the predicted intracellular/cytosolic region of the protein. LSMEM2 has a predicted N-glycosylation site at amino acids 155,156, and 157 in the probable extracellular/lumenal region.Structure
The secondary and tertiary structure of LSMEM2 are currently unknown. The secondary structure is predicted as largely alpha-helices for the transmembrane and lumenal/extracellular region. The cytoplasmic/intracellular region structure still remains relatively unclear. To the right is a predicted tertiary structure of the human LSMEM2 protein by the I-TASSER software.Homology
ParalogsLSMEM2 has no known paralogs.
Orthologs
LSMEM2 has 168 orthologs total, 131 of them being mammals, the other orthologs consist of aves and reptiles The LSMEM2 protein is conserved in mammals with 71.3% chemically-similar sequences. The table below displays features of select orthologs of LSMEM2 of varying evolutionary distance. The predicted transmembrane domain of LSMEM2 is found to be highly conserved in its orthologs.
| Genus and species | Common name | Accession number | Length | Sequence Identity | Sequence Similarity | Date of Divergence |
| Homo sapiens | Human | NP_001291314.1 | 163 | 100% | 100% | 0 |
| Acinonyx jubatus | Cheetah | XP_014932576 | 149 | 84.11% | 85.30% | 105 |
| Ornithorhynchus anatinus | Platypus | XP_028906032 | 172 | 67.97% | 71.30% | 177 |
| Gallus gallus | Chicken | XP_015148980.1 | 159 | 50.00% | 41.20% | 312 |
| Chrysemys picta | Painted turtle | XP_005308817 | 172 | 39.53% | 44.10% | 312 |