DEPDC1B

The DEPDC1B gene possesses two novel proteoforms. The longest variation, coded by mRNA isoform 1, is the most commonly used. The protein is 529 amino acids in length. The second novel proteoform, DEPDC1B.2 is coded by 10 exons, missing the 10th exon from the longest variation. The protein is 467 amino acids in length. The missing 62 amino acids follow the RhoGAP domain, in a region predicted to be highly phosphorylated^[15]

DEPDC1B contains two structural domains: a DEP domain and a RhoGAP domain.

The DEP domain is primarily found in proteins involved in G-protein signalling pathways and regulation of GTPase.^[16][17] As well, experimental evidence suggests that the DEP domain determines the subcellular target of some GTPase Activating proteins.^[18] In the DEPDC1B protein electronic inference has verified the GTPase activator activity function.^[15] The solution structure of human containing DEP domain containing proteins verifies the secondary structure of the domain: containing three alpha-helices and two beta-strands within the approximate 80 amino acid region of the domain.^[19][20]

The RhoGAP domain is another structural domain known to interact with GTPase and small GTPase. Research concerning the domain in other proteins indicates an approximately similar function among the domain in various proteins. The domain has been verified to interact with other proteins to form complexes or interact with other structures of the cell such as the cytoskeleton or plasma membrane.^[21]

DEPDC1B protein product is predicted to be highly phosphorylated after translation.^[22] A single sumoylation site, found within the RhoGAP domain, indicates the possible interaction of the protein with a SUMO protein, enabling or inhibiting interaction with other proteins.^[23] A single palmitoylation site, found within the RhoGAP domain, indicates the possible interaction of the DEPDC1B protein product with a membrane via lipid anchor.^[24]

No conserved glycosylation sites are predicted within the mature DEPDC1B protein product.^[25] No signal peptide or transmembrane domains are predicted within human or any ortholog protein.^[26][27] No prenylation sites are predicted in any DEPDC1B orthologs.^[28]

Expression of DEPDC1B is reported to be largely ubiquitous throughout mouse tissue. High level of gene expression is observed in all periods of life, except early zygote stages.^[8] Experimental evidence suggests that DEPDC1B presents similar ubiquitous expression in all tissues.^[29]

Differential expression profiles suggest that DEPDC1B is higher expressed in many cancerous disease states, including: papillary thyroid cancer,^[30] breast cancer,^[31] synovial sarcoma,^[32] and prostatic cancer progression.^[33] Also, DEPDC1B expression decreases in environments of beta-catenin depletion in multiple myeloma cell lines^[34]

No interactions of DEPDC1B within any other protein product characterized by experimentation have been verified.^[35]

Medium coexpression of DEPDC1B with ECT2 in cell cycle regulation and DNA synthesis was verified by similarity of expression in various tissues.^[35] The remaining predicted interaction were determined via datamining.

DEPDC1B is unique to Chordates in Kingdom Animalia^[36]

Multiple sequence alignments verify that DEPDC1B is highly conserved among orthologs.^{[37][38][39][40]} The two structural domains (DEP and RhoGAP) are the two most conserved elements of the proteins. Various motifs are also conserved throughout the protein. No data suggesting motif function could be determined. All predicted post-translational modification were confirmed to be conserved in the orthologous proteins.

DEPDC1B evolution is predicted to follow the general species evolution.

DEPDC1B possesses two significant paralogs - DEPDC1A and DEPDC7

Multiple sequence alignment and phylogenetic analysis indicates DEPDC1A as the most recent paralog, diverging approximately 600 million years ago. DEPDC1A has been researched in several disease states. High expression of the protein in Multiple Myeloma (MM) malignant plasma cells is associated with patient fatality. The high expression has been confirmed using conditional lentiviral vector delivery "to inhibit growth of human melanoma cell lines (HMCLs), with a block in G2 phase of the cell cycle, p53 phosphorylation and stabilization, and p21Cip1 accumulation"9.^[42] In the same study it was concluded that DEPDC1A may contribute to the plasmablast features of MM cells, blocking differentiation. Study of DEPDC1A in bladder carcinogenesis revealed the gene as a possible antigen for the formation of bladder cancer cells. Using microarray and northern blotting confirmed the presence of unsubstantial amounts of the protein within the normal tissues, excluding the testis. Currently the gene is a potential target molecule for therapeutic treatment of bladder carcinogenesis.^[43]

No data detailing significant function in DEPD7 has been published or recorded.