Leucine rich repeat containing 40 (LRRC40) is a protein that in humans is encoded by the LRRC40 gene.[1]
LRRC40 is conserved throughout all of its orthologs. The entire protein is highly conserved in mammals, while conservation is high within the leucine rich repeats in the rest of the orthologs.[2] Orthologs were found all the way back to the scarlet sea anemone and homologs were found in bacteria and Archaea using BLAST.[3] The following table gives information on the homologs of LRRC40.
| Organism common name | Divergence from humans (MYA) [4] | NCBI mRNA accession | Sequence similarity | Protein length | Common gene name | ||
|---|---|---|---|---|---|---|---|
| Homo sapiens[5] | Humans | -- | NM_017768 | 100% | 602 | LRRC40 | |
| Pan troglodytes[6] | Common chimp | 6.4 | XM_513483 | 99% | 602 | Hypothetical protein | |
| Pongo abelii [7] | Orangutan | 15.8 | NM_001131180 | 99% | 602 | LRRC40 | |
| Macaca fascicularis [8] | Long-tailed macaque | 30.2 | AB179219 | 99% | 602 | Full LRRC40 | |
| Callithrix jacchus [9] | Common marmoset | 43.9 | XM_002750952.1 | 99% | 602 | Predicted: LRRC40 | |
| Sus scrofa [10] | Wild boar | 92.5 | XM_003127928 | 96% | 602 | Predicted: LRRC40 like protein | |
| Mus musculus [11] | Mouse | 94.1 | NM_024194 | 92% | 602 | LRRC40 | |
| Monodelphis domestica [12] | Opossum | 160.2 | XM_001379417 | 86% | 598 | Hypothetical protein | |
| Gallus gallus [13] | Chicken | 274.8 | NM_001031295 | 85% | 603 | LRRC40 | |
| Taeniopygia guttata [14] | Zebra finch | 274.8 | XM_002188367 | 85% | 605 | Predicted: LRRC40 | |
| Xenopus (Silurana) tropicalis [15] | Western clawed frog | 389.7 | NM_001011310 | 80% | 605 | LRRC40 | |
| Danio rerio [16] | Zebrafish | 444.3 | NM_199862 | 83% | 601 | LRRC40 | |
| Salmo salar [17] | Salmon | 444.3 | BT043621 | 82% | 600 | LRRC40 | |
| Nematostella vectensis [18] | Scarlet sea anemone | 830.3 | XM_001640230 | 66% | 602 | Predicted protein | |
| Culex quinquefasciatus [19] | Southern house mosquito | 838.3 | XM_001842697.1 | 58% | 612 | LRRC40 |
LRRC40 is located on the negative DNA strand (see Sense (molecular biology)) of chromosome 1 from 70,611,483- 70,671,223.[20] The gene produces a 2958 base pair mRNA. There are 15 predicted exons in the human gene [5] with four other splice patterns predicted on GeneCards by the Alternative Splice Database.[21]
LRRC40 is neighbored downstream by LRRC7 (70,225,888 - 70,587,570) on the positive DNA strand and upstream by SRSF11 (70,687,320-70,716,488) on the positive DNA strand.
LRRC40 is expressed between the 50th and 100th percentile in almost every tissue in the body.[22]
While the exact function of the LRRC40 protein is not yet understood, it is believed to participate in protein-protein interactions because it is a member of the leucine rich repeat family of proteins which are known to participate in protein-protein interactions.[23]
LRRC40 is a 602 amino acid protein with a molecular weight of 68.254 kDa and an isoelectric point of 6.04.[24] LRRC40 is expected to localize to the nucleus[25] and has no transmembrane domains to anchor it to the nuclear membrane. LRRC40 has many predicted phosphorylation sites. Of the 19 predicted phosphoserine sites, only two are conserved within the orthologs.[26] These two sites are S38 and S391.
The secondary structure of the protein has a pattern within the leucine repeat regions. Each leucine repeat has a β-sheet and α-helix. The image to the right shows the particular horseshoe-like structure of a protein with many leucine rich repeats. Depending on the area where the LRRs are located, other proteins can bind within the curve of the horseshoe or attach to the outside of the protein.
According to Genecards, LRRC40 has 756 possible protein interactions.[21] These interactions are based on results in the Molecular Interaction database which provided two possible protein interactions. The two proteins are described in the table below.
| Abbreviation | Protein name | NCBI protein accession | Cellular location | Function | |
|---|---|---|---|---|---|
| Cell division cycle 5-like protein | NP_001244 | nucleus | transcription regulation and mRNA processing [27] | ||
| Ski-interacting protein | NP_036377.1 | nucleus | mRNA processing [28] |