Draft:Testis Expressed Protein 44

Tex44 is a protein which in humans is encoded by the c2orf57 gene. Tex44 located on the second chromosome in humans, encodes the protein Tex44. The protein is part of the Testis Expressed protein family and thus is involved in spermatogenesis. The protein is found in orthologs within the mammalia classification. A lack of expression of this protein has been association with higher occurrences of reproductive cancers such as uterine cancer and asthenozoospermia

Locus
Tex44 is located on chromosome two at position 23q37.1. The exact location of the gene is at chr2:231,592,864-231,594,276. Common alias include Tex44 and chromosome 2 open reading frame 57 (c2or57). The gene contains one exon spanning the entire 1413 base pairs sequence. Tex44 is plus stand orientated

Gene neighborhood
Genes located nearby c2or57 include COPS7B, B3GNT7, NPPCM and NGURI. Significance of nearby genes include encoding nucleoplasmic and integral membrane proteins.

Tissue of expression
Tex44 displays low expression in all tissues with highest expression levels in the testis. Medium expression above all tissue levels can be found in the pancreas, thyroid, spleen, salivary glands, and breast tissue.

Size
Tex44 is 396 amino acids long with a molecular weight of 41589 Da. Additionally there are 4 disordered regions and one phosphorylation site. The protein is serine rich but cysteine and phenylalanine poor.

Subcellular localization
This protein is localized in the cytoplasm. This is confirmed with the presence of known nuclear export signals identified in the latter end portion of the protein sequence. These export signals along side no presence of transmembrane domains further reiterate that Tex44 is localized in the cytoplasm.

Secondary structure
In humans this protein is composed predominantly of alpha helices and beta sheets. There are 6 alpha helix structures present within the amino acid chain and 1 beta sheet. Both the alpha helices and beta sheets are located within the last 200 amino acids of the protein sequence.

Tertiary structure
Current predictions of Tex44 tertiary structures have 81% of the protein being comprised of disordered regions. Due to this large percentage of the protein being disordered a confirmed tertiary structure cannot be identified. Predicted results can be found in the image as followed.

Post translational modifications
Human Tex44 undergoes phosphorylation, sumoylation, and propionylation. Since the protein is identified to have high levels of serine, high presence of phosphorylation sites are common.

Homology
Tex44 orthologs are only present in mammals and its three subclassifications, placentals, marsupials, and monotremes. The largest cluster of orthologs are present in the placental mammal classification with less being found in the more evolutionary distant groups, marsupial and monotremes, relative to humans. There are currently no known paralogs of this protein. The table as followed displays only 20 of the many orthologs of Tex44.

Function
Tex44 has been identified to be a protein integral to the formation, maturation, and function of sperm tissue. Suppression of Tex44 has been linked to immobilized sperm and therefore infertility.

Interacting proteins
Several proteins have been identified to interact with Tex44. SYPL1, DERL1, NAA11, Tex37, GPR157, MPC2, and SPATA3 are all interacting proteins involved in germ cell maturation. Other interacting proteins such as APOC1 an TIMM17B are known to be involved in other tissue development such as the pancreas, placenta, lungs and spleen

Pathology
Ubiquitous expression of Tex44 has been observed in various cancers such as breast, uterine, and pancreatic. Low expression of Tex44 is known to cause infertility via Teratozoospermia.