FAM203B-Cedar Herald Index

Family with Sequence Similarity 203, Member B (FAM203B) is a protein encoded by the FAM203B gene (8q24.3) in humans. While FAM203B is only found in humans and possibly non-human primates, its paralog, FAM203A, is highly conserved. The FAM203B protein contains two conserved domains of unknown function, DUF383 and DUF384, and no transmembrane domains. This protein has no known function yet, although the homolog of FAM203A in Caenorhabditis elegans (Y54H5A.2) is thought to help regulate the actin cytoskeleton.

Gene

FAM203B is located on the positive DNA strand of the long arm of chromosome 8 at locus 24.3 (8q24.3) from 76,368,898 - 76,371,411 in the human genome. The gene product contains 2,402 bp of mRNA with 6 predicted exons in the human gene. There are no known isoforms.

FAM203B

Gene Neighborhood

The pseudogene TSSK5P2 is located on the negative strand opposite FAM203B (145,440,975 - 145,443,775), while LOC377711 is located immediately downstream on the positive strand (145,448,755 - 145,485,896). FAM203A, MROH1, and SCXB are located upstream of FAM203B.

FAM203B

Gene Expression

Expression Profile: mRNA expression has been localized in many tissue types (immune, nervous, muscle, internal, secretory, and reproductive) in similar quantities and may therefore be ubiquitous.

FAM203B

Promoter: The predicted promoter region of FAM203B is located between 145,437,380 and 145,438,015 on Chromosome 8 and has a length of 636 bp.

Protein

The function of FAM203B is not currently understood. The FAM203B protein has 390 amino acids, a molecular weight of 42.1 kdal, and an isoelectric point of 4.56.

Structure

FAM203B contains two domains of unknown function: DUF383 (residues 110–288) and DUF384 (residues 292–349). The protein is alanine-, proline-, and leucine-rich, but poor in serine, asparagine, threonine, isoleucine, lysine, and phenylalanine. The following internal repeats can be found in the primary sequence: LPFL (26-29, 245–248), ELAP (70-73), GRAL (54-57, 111–114), and LAADPGL (88-94, 99–105). There are no positive, negative, mixed charge, or hydrophobic clusters; no transmembrane domains; and no clusters of amino acid multiplets. The secondary structure prediction generated by the Phyre 2.0 bioinformatic server shows only α-helices, almost all of which have high confidence values. The overall confidence value of the model is 99.5%.

Post-Translational Modifications

There are at least six predicted phosphorylation sites in FAM203B: S17, S153, Y167, T223, S259, and S320. The FAM203B protein is also predicted to locate to the cytoplasm.

Protein Interactions

There are many possible transcription factor binding sites in the FAM203B promoter. Below is a table of the best possibilities, which have high confidence values, evolutionary conservation, and/or multiple possible binding sites in the promoter.

Table of Possible Transcription Factor Binding Sites in Predicted FAM203B Promoter:

There are several other proteins that may interact directly with the FAM203B protein including C1orf112, HEATR3, MRTO4, BYSL, GINS1, DKC1, TXNDC12, PWP2, IMP4, and NIP7.

Homology and Evolution

FAM203A: Paralog

FAM203A is 99% identical to FAM203B with only one amino acid difference (E264Q) due to a point mutation (G857C). This indicates that the duplication event that produced FAM203B 242,266 bp downstream from FAM203A occurred very recently in evolutionary history. The FAM203A protein is highly conserved and has orthologs in primates, rodents, ungulates, marsupials, amphibians, fish, fungi, plants, and at least one monotreme, one reptile, and one hemichordate.