GRASP55 explained

Golgi reassembly-stacking protein of 55 kDa (GRASP55) also known as golgi reassembly-stacking protein 2 (GORASP2) is a protein that in humans is encoded by the GORASP2 gene.^{[1] [2]} It was identified by its homology with GRASP65 and the protein's amino acid sequence was determined by analysis of a molecular clone of its complementary DNA.^[1] The first (N-terminus) 212 amino acid residues of GRASP55 are highly homologous to those of GRASP65, but the remainder of the 454 amino acid residues are highly diverged from GRASP65.^[1] The conserved region is known as the GRASP domain, and it is conserved among GRASPs of a wide variety of eukaryotes, but not plants.^{[2] [3]} The C-terminus portion of the molecule is called the SPR domain (serine, proline-rich).^[3] GRASP55 is more closely related to homologues in other species, suggesting that GRASP55 is ancestral to GRASP65.^[3] GRASP55 is found associated with the medial and trans cisternae of the Golgi apparatus.^[3]

Function

GRASP55 is involved in establishing the structure of the Golgi apparatus.^{[3] [2]} It is a peripheral membrane protein located on the Golgi cisterna, and it can bind to another GRASP55 located on an adjacent cisterna through the GRASP domain, thus linking the cisternae together through multiple protein–protein interactions.^{[3] [4]}

GRASP55 is attached to the membrane in two ways; it is myristylated, which attaches it directly to the lipid bilayer; it is also bound indirectly by binding to golgin-45, which binds to a Rab protein, which itself is lipidated and thus anchored to the membrane.^[3]

The structure of the Golgi is disrupted during mitosis, and phosphorylation of the SPR domains of GRASP55 and GRASP65 regulate that disruption,^{[5] [4]} GRASP55 may also be involved in forming Golgi ribbons, but the evidence is mixed.^{[3] [5]}

Other interactions

GRASP55 has been shown to interact with TGF alpha,^[6] TMED2^[6] and GOLGA2.^{[6] [7]}

Further reading

• Maruyama K, Sugano S . Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides . Gene . 138 . 1–2 . 171–4 . January 1994 . 8125298 . 10.1016/0378-1119(94)90802-8 .
• Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S . Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library . Gene . 200 . 1–2 . 149–56 . October 1997 . 9373149 . 10.1016/S0378-1119(97)00411-3 .
• Kuo A, Zhong C, Lane WS, Derynck R . Transmembrane transforming growth factor-alpha tethers to the PDZ domain-containing, Golgi membrane-associated protein p59/GRASP55 . The EMBO Journal . 19 . 23 . 6427–39 . December 2000 . 11101516 . 305863 . 10.1093/emboj/19.23.6427 .
• Jesch SA, Lewis TS, Ahn NG, Linstedt AD . Mitotic phosphorylation of Golgi reassembly stacking protein 55 by mitogen-activated protein kinase ERK2 . Molecular Biology of the Cell . 12 . 6 . 1811–7 . June 2001 . 11408587 . 37343 . 10.1091/mbc.12.6.1811 .
• Short B, Preisinger C, Körner R, Kopajtich R, Byron O, Barr FA . A GRASP55-rab2 effector complex linking Golgi structure to membrane traffic . The Journal of Cell Biology . 155 . 6 . 877–83 . December 2001 . 11739401 . 2150909 . 10.1083/jcb.200108079 .
• Barr FA, Preisinger C, Kopajtich R, Körner R . Golgi matrix proteins interact with p24 cargo receptors and aid their efficient retention in the Golgi apparatus . The Journal of Cell Biology . 155 . 6 . 885–91 . December 2001 . 11739402 . 2150891 . 10.1083/jcb.200108102 .
• Lane JD, Lucocq J, Pryde J, Barr FA, Woodman PG, Allan VJ, Lowe M . Caspase-mediated cleavage of the stacking protein GRASP65 is required for Golgi fragmentation during apoptosis . The Journal of Cell Biology . 156 . 3 . 495–509 . February 2002 . 11815631 . 2173349 . 10.1083/jcb.200110007 .
• Beausoleil SA, Villén J, Gerber SA, Rush J, Gygi SP . A probability-based approach for high-throughput protein phosphorylation analysis and site localization . Nature Biotechnology . 24 . 10 . 1285–92 . October 2006 . 16964243 . 10.1038/nbt1240 . 14294292 .
• Olsen JV, Blagoev B, Gnad F, Macek B, Kumar C, Mortensen P, Mann M . Global, in vivo, and site-specific phosphorylation dynamics in signaling networks . Cell . 127 . 3 . 635–48 . November 2006 . 17081983 . 10.1016/j.cell.2006.09.026 . 7827573 . free .

Notes and References

1. Shorter J, Watson R, Giannakou ME, Clarke M, Warren G, Barr FA . GRASP55, a second mammalian GRASP protein involved in the stacking of Golgi cisternae in a cell-free system . The EMBO Journal . 18 . 18 . 4949–60 . September 1999 . 10487747 . 1171566 . 10.1093/emboj/18.18.4949 .
2. Web site: Entrez Gene: GORASP2 golgi reassembly stacking protein 2, 55kDa .
3. Zhang X, Wang Y . GRASPs in Golgi Structure and Function . Frontiers in Cell and Developmental Biology . 3 . 84 . 2015 . 26779480 . 4701983 . 10.3389/fcell.2015.00084 . free .
4. Zhang. Xiaoyan. Wang. Yanzhuang. GRASPs in Golgi Structure and Function. Frontiers in Cell and Developmental Biology. 3. 84. 10.3389/fcell.2015.00084. 26779480. 4701983. 6 January 2016. free .
5. Xiang Y, Wang Y . GRASP55 and GRASP65 play complementary and essential roles in Golgi cisternal stacking . The Journal of Cell Biology . 188 . 2 . 237–51 . January 2010 . 20083603 . 2812519 . 10.1083/jcb.200907132 .
6. Barr FA, Preisinger C, Kopajtich R, Körner R . Golgi matrix proteins interact with p24 cargo receptors and aid their efficient retention in the Golgi apparatus . The Journal of Cell Biology . 155 . 6 . 885–91 . December 2001 . 11739402 . 2150891 . 10.1083/jcb.200108102 .
7. Short B, Preisinger C, Körner R, Kopajtich R, Byron O, Barr FA . A GRASP55-rab2 effector complex linking Golgi structure to membrane traffic . The Journal of Cell Biology . 155 . 6 . 877–83 . December 2001 . 11739401 . 2150909 . 10.1083/jcb.200108079 .