ABHD18 is a protein that in Homo sapiens is encoded by the ABHD18 gene.[5]
Gene
ABHD18 is found on the positive strand of the human genome at 4q28.2. It is 74.4 kbp. The gene contains 17 exons.[6] The longest mRNA transcript is composed of 13 exons and is 2200 base pairs.[5]
Homology
Orthologs
Many orthologs to human ABHD18 have been discovered, with the most distant ortholog with high (over 90%) coverage is found in rice Oryza sativa.[8] The protein is not found in fungi. Bacteria of the order Myxobacteria and genus Chitinimonas contain orthologous regions to the C4orf29 protein. The few bacterial homologs indicate a horizontal gene transfer event. The domain of unknown function, DUF2048, is conserved throughout orthologs.
ABHD18 codes a 414 amino acid sequence of 46.9 kDa in humans. The predicted isoelectric point is 9.37.[10] The domain of unknown function, DUF2048, is found from amino acid residues 25 to 414 in the precursor C4orf29 protein.[11] This domain is part of the alpha/beta hydrolase superfamily, which comprises enzymes that catalyze fat metabolism. Predicted post-translational modifications include glycosylation at residues Ser287 and Ser319 [12] and sumoylation[13] at the motifs Phe240 to Gly243, Ala377 to Asp340, and Phe408 to Gly411.
Expression
The protein product of ABHD18 in humans is predicted to be a secreted product. It is ubiquitously expressed at low to moderate levels.[14] In humans, the protein is found at high levels the digestive tract and parathyroid gland.[15] The homologous mouse protein 3110057O12Rik is expressed at high levels in the granule layer of the cerebellum.[16]
Clinical significance
ABHD18 contains highly variable numbers of Alu repeats.[17] A low number of Alu repeats in the human ABHD18 protein is associated with increase prevalence of hepatocellular carcinoma (HCC) in Asian populations. This information is used as a genetic marker to determine genetic risk of HCC.[18]
Swine muscle transcriptome analysis indicates high expression of ABHD18 in swine with extreme low levels of fatty acid composition.[19]
References
^ a b cGRCh38: Ensembl release 89: ENSG00000164074 – Ensembl, May 2017
^ a b cGRCm38: Ensembl release 89: ENSMUSG00000037818 – Ensembl, May 2017
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ a b"C4orf29". NCBI Gene. NCBI. Retrieved 5 May 2015.
^"C4orf29". NCBI AceView. Retrieved 2015-05-05.
^"C4orf29". GeneCards Human Gene Database.
^"NP_001034806". NCBI Protein BLAST.
^Kelley LA, Sternberg M (2009). "Protein structure prediction on the web: a case study using the Phyre server". Nature Protocols. 4 (3): 363–371. doi:10.1038/nprot.2009.2. hdl:10044/1/18157. PMID 19247286. S2CID 12497300. Retrieved 16 Apr 2015.