@article {Herbomel071225, author = {Gaetan G. Herbomel and Raul E. Rojas and Duy T. Tran and Monica Ajinkya and Lauren Beck and Lawrence A. Tabak}, title = {Growth Factors do not regulate Golgi Complex-to-ER relocation of GalNAc-Ts in HeLa cells}, elocation-id = {071225}, year = {2016}, doi = {10.1101/071225}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Mucin-type O-glycosylation is initiated by the UDP-GalNAc polypeptide:N-acetylgalactosaminyltransferase (GalNAc-T) family of enzymes. Their activity results in the GalNAc α1-O-Thr/Ser structure, termed the Tn antigen, which is further decorated with additional sugars. In neoplastic cells, the Tn antigen is often overexpressed. Because O-glycosylation is controlled by the activity of GalNAc-Ts, their regulation is of great interest. Previous reports suggest that growth factors, EGF or PDGF, induce Golgi complex-to-endoplasmic reticulum (ER) relocation of both GalNAc-Ts and Tn antigen in HeLa cells, offering a mechanism for Tn antigen overexpression termed {\textquotedblleft}GALA{\textquotedblright}. However, we were unable to reproduce these findings. Upon treatment of HeLa cells with either EGF or PDGF we observed no change in the co-localization of endogenous GalNAc-T1, GalNAc-T2 or Tn antigen with the Golgi complex marker TGN46. There was also no enhancement of localization with the ER marker calnexin. We conclude that growth factors do not cause redistribution of GalNAc-Ts from the Golgi complex to the ER in HeLa cells.GalNAc-TUDP-GalNAc polypeptide:N acetylgalactosaminyltransferaseGalNAcN-acetylgalactosamineEREndoplasmic reticulumEGFEpidermal growth factorPDGFPlatelet-derived growth factorMAPKMitogen-activated protein kinaseNANumerical aperatureAUAiry unitMCCManders{\textquoteright} correlation coefficient}, URL = {https://www.biorxiv.org/content/early/2016/08/23/071225}, eprint = {https://www.biorxiv.org/content/early/2016/08/23/071225.full.pdf}, journal = {bioRxiv} }