GOLM1 explained

Golgi membrane protein 1 (GOLM1) also known as Golgi phosphoprotein 2 or Golgi membrane protein GP73 is a protein that in humans is encoded by the GOLM1 gene.^{[1] [2] [3]} Two alternatively spliced transcript variants encoding the same protein have been described for this gene.

Function

The Golgi complex plays a key role in the sorting and modification of proteins exported from the endoplasmic reticulum. The protein encoded by this gene is a type II Golgi transmembrane protein. It processes protein synthesized in the rough endoplasmic reticulum and assists in the transport of protein cargo through the Golgi apparatus. The expression of this encoded protein has been observed to be upregulated in response to viral infection.^[3]

Clinical significance

Golgi membrane protein 1 is overexpressed in prostate cancer^{[4] [5]} and lung adenocarcinoma tissue.^[6]

Blood levels of GP73 are higher in patients with liver cancer than in healthy individuals. In addition, levels were not significantly higher in patients with diseases other than liver disease. The current blood test used to screen for early tumors in people at high risk for liver cancer involves the alpha-fetoprotein (AFP). Patients who are at risk for non-metastatic, or primary, liver cancer typically have chronic liver disease such as cirrhosis. Such cases of cirrhosis are usually due to infection caused by infectious hepatitis (usually hepatitis B or hepatitis C, though there are other strains), or because of degenerative fatty liver disease (which can be especially severe in those with alcoholism). However, the AFP test is not usually sensitive enough to detect liver cancer in time and it often generates false positives. So far, the blood samples of more than 1,000 patients with various stages of liver and non-liver disease have been tested for the presence of GP73 in several studies. Several medical diagnostic companies are in the process of developing automated serum tests for the protein that could be performed in routine hospital laboratories.^[7]

Further reading

• Kladney RD, Cui X, Bulla GA, Brunt EM, Fimmel CJ . Expression of GP73, a resident Golgi membrane protein, in viral and nonviral liver disease . Hepatology . 35 . 6 . 1431–40 . June 2002 . 12029628 . 10.1053/jhep.2002.32525 . 27638187 .
• Bauer K, Zemlin M, Hummel M, Pfeiffer S, Karstaedt J, Steinhauser G, Xiao X, Versmold H, Berek C . Diversification of Ig heavy chain genes in human preterm neonates prematurely exposed to environmental antigens . Journal of Immunology . 169 . 3 . 1349–56 . August 2002 . 12133958 . 10.4049/jimmunol.169.3.1349 . free .
• Puri S, Bachert C, Fimmel CJ, Linstedt AD . Cycling of early Golgi proteins via the cell surface and endosomes upon lumenal pH disruption . Traffic . 3 . 9 . 641–53 . September 2002 . 12191016 . 10.1034/j.1600-0854.2002.30906.x . 38956403 . free .
• Kladney RD, Tollefson AE, Wold WS, Fimmel CJ . Upregulation of the Golgi protein GP73 by adenovirus infection requires the E1A CtBP interaction domain . Virology . 301 . 2 . 236–46 . September 2002 . 12359426 . 10.1006/viro.2002.1523 . free .
• Zhang H, Li XJ, Martin DB, Aebersold R . Identification and quantification of N-linked glycoproteins using hydrazide chemistry, stable isotope labeling and mass spectrometry . Nature Biotechnology . 21 . 6 . 660–6 . June 2003 . 12754519 . 10.1038/nbt827 . 581283 .
• Otsuki T, Ota T, Nishikawa T, Hayashi K, Suzuki Y, Yamamoto J, Wakamatsu A, Kimura K, Sakamoto K, Hatano N, Kawai Y, Ishii S, Saito K, Kojima S, Sugiyama T, Ono T, Okano K, Yoshikawa Y, Aotsuka S, Sasaki N, Hattori A, Okumura K, Nagai K, Sugano S, Isogai T . Signal sequence and keyword trap in silico for selection of full-length human cDNAs encoding secretion or membrane proteins from oligo-capped cDNA libraries . DNA Research . 12 . 2 . 117–26 . 2007 . 16303743 . 10.1093/dnares/12.2.117 . free .
• Ramachandran P, Boontheung P, Xie Y, Sondej M, Wong DT, Loo JA . Identification of N-linked glycoproteins in human saliva by glycoprotein capture and mass spectrometry . Journal of Proteome Research . 5 . 6 . 1493–503 . June 2006 . 16740002 . 10.1021/pr050492k .
• Bachert C, Fimmel C, Linstedt AD . Endosomal trafficking and proprotein convertase cleavage of cis Golgi protein GP73 produces marker for hepatocellular carcinoma . Traffic . 8 . 10 . 1415–23 . October 2007 . 17662025 . 10.1111/j.1600-0854.2007.00621.x . 27491613 . free .
• Gu Y, Chen W, Zhao Y, Chen L, Peng T . Quantitative analysis of elevated serum Golgi protein-73 expression in patients with liver diseases . Annals of Clinical Biochemistry . 46 . Pt 1 . 38–43 . January 2009 . 19008260 . 10.1258/acb.2008.008088 . free .
• Zhou Y, Li L, Hu L, Peng T . Golgi phosphoprotein 2 (GOLPH2/GP73/GOLM1) interacts with secretory clusterin . Molecular Biology Reports . 38 . 3 . 1457–62 . March 2011 . 20842452 . 10.1007/s11033-010-0251-7 . 22823938 .

Notes and References

1. Kladney RD, Bulla GA, Guo L, Mason AL, Tollefson AE, Simon DJ, Koutoubi Z, Fimmel CJ . GP73, a novel Golgi-localized protein upregulated by viral infection . Gene . 249 . 1–2 . 53–65 . May 2000 . 10831838 . 7127640 . 10.1016/S0378-1119(00)00136-0 .
2. Varambally S, Laxman B, Mehra R, Cao Q, Dhanasekaran SM, Tomlins SA, Granger J, Vellaichamy A, Sreekumar A, Yu J, Gu W, Shen R, Ghosh D, Wright LM, Kladney RD, Kuefer R, Rubin MA, Fimmel CJ, Chinnaiyan AM . Golgi protein GOLM1 is a tissue and urine biomarker of prostate cancer . Neoplasia . 10 . 11 . 1285–94 . November 2008 . 18953438 . 2570605 . 10.1593/neo.08922 .
3. Web site: Entrez Gene: GOLPH2 golgi phosphoprotein 2.
4. Laxman B, Morris DS, Yu J, Siddiqui J, Cao J, Mehra R, Lonigro RJ, Tsodikov A, Wei JT, Tomlins SA, Chinnaiyan AM . A first-generation multiplex biomarker analysis of urine for the early detection of prostate cancer . Cancer Research . 68 . 3 . 645–9 . February 2008 . 18245462 . 2998181 . 10.1158/0008-5472.CAN-07-3224 .
5. Wei S, Dunn TA, Isaacs WB, De Marzo AM, Luo J . GOLPH2 and MYO6: putative prostate cancer markers localized to the Golgi apparatus . The Prostate . 68 . 13 . 1387–95 . September 2008 . 18543251 . 4124602 . 10.1002/pros.20806 .
6. Zhang F, Gu Y, Li X, Wang W, He J, Peng T . Up-regulated Golgi phosphoprotein 2 (GOLPH2) expression in lung adenocarcinoma tissue . Clinical Biochemistry . 43 . 12 . 983–91 . August 2010 . 20501332 . 10.1016/j.clinbiochem.2010.05.010 .
7. Web site: New biomarker could lead to the world's first reliable test for liver cancer . 2010-04-08 . Loyola Medicine News Release . Loyola University Medical Center . https://web.archive.org/web/20110720125538/http://www.loyolamedicine.org/News/News_Releases/news_release_detail.cfm?var_news_release_id=973441154 . 2011-07-20 . 2011-05-07 . dead .