TEX55

The TEX55 gene is 13,893 bp and spans from base pair 119,146,151 to 119,160,042.^[6] This gene is flanked by immunoglobulin superfamily member 11 and Uroplakin1B.^[5]

The promoter region of TEX55 has multiple SRY box-6 and SOX/SRY-sex/testis determining and related HMG box transcription factor binding sites, as well as an X-linked zinc finger binding site. This indicates that the sex chromosomes may play a role in post-translational modification and expression.^[7]

The TEX55 protein has no known human paralogs.^[8]

TEX55 has orthologs in many mammals including, bats, dolphins, and even aardvarks.^[8] According to BLAST the TEX55 protein cannot be found outside of clade Mammalia.^[8] The most distant ortholog, found using BLAST, was in the aardvark, which is thought to have diverged an estimated 105 MYA.^[9] However, according to GeneCard, distant orthologs have also been found in chickens, lizards (Anolis carolinensis), and zebrafish.^[6]

The mRNA of TEX55 is 1800 base pairs long and has three exons.^[6] According to GeneCard, the TEX55 mRNA has 3 theoretical splice forms, but only the one containing all three exons have been studied and characterized.^[6] The 5’ UTR of the mRNA has an RFX1 binding site, which binds to a stem-loop structure just upstream of the start codon, used to activate transcription.^[7][10]

The translated protein of the TEX 55 mRNA is 536 AA, a predicted molecular weight of 60 kD, had an isoelectric point of 5.51, and is highly conserved at the C-terminus.^[11] Tex55 has a slightly high amount of Glutamine and a slightly low amount of Leucine, which compared to the protein database swp23s.q.^[11] Multiple sequence alignment of TEX55 and 20 mammalian orthologs show that there are 28 residues, concentrated in the C-terminus, that are conserved between all proteins.^[8][12] The highly conserved residues are outlined in the conceptual translation and multiple sequence analysis. Through function-region analysis, researchers found that this protein may act as an anchoring protein of cAMP-dependent type-II PK, and might be an A-kinase anchoring proteins.^[13][14]

Analysis of the sumoylation sites indicate that Lys 14 has a high probability of being sumoylated.^[17] The TEX55 protein has a high number of potential phosphorylation/O-glycosylation sites.^[18][19]

All secondary structure prediction analysis indicate that the C-terminus of Tex 55 has a high probability of being an alpha-helix, and indicate that there is little to no amount of beta-sheets. Secondary structure analysis tools predict that the majority of the Tex 55 protein is coiled domains, and alpha-helices.

Tertiary structures of TEX55 was generated using Phyre2. The C-terminus, which is highly conserved, was calculated to have a 30 residue alpha-helix that has relatively high confidence (82.3%). The highly conserved, high-confidence, alpha-helix is colored in red in the 3D structure image of TEX55 to the above. The overall tertiary structure of TEX55 is globular.

Tex55 has two motifs according to GeneCard: EF-Hand Calcium Binding Domain 10 and Uroplakin 1B, both of which are found in the middle of the protein.^[6] Uroplakin 1B is known to regulate cell development, activation, growth, and motility.^[20] This could indicate why abnormalities in TEX55 expression leads to sperm with altered morphology.^[13][21]

Analysis the cellular localization probability of Tex55 and its orthologs indicate that it is most likely located in the nucleus of the cell. Below is a list of orthologs and the probability of finding that protein in the specified cellular location.^[22]