Germ cell-specific gene 1 targets testis-specific poly(A) polymerase to the endoplasmic reticulum through protein-protein interactions

FEBS Lett. 2008 Apr 9;582(8):1203-9. doi: 10.1016/j.febslet.2008.01.065. Epub 2008 Mar 4.


Testis-specific poly(A) polymerase (TPAP) is a cytoplasmic poly(A) polymerase that is highly expressed in round spermatids. We identified germ cell-specific gene 1 (GSG1) as a TPAP interaction partner protein using yeast two-hybrid and coimmunoprecipitation assays. Subcellular fractionation analysis showed that GSG1 is exclusively localized in the endoplasmic reticulum (ER) of mouse testis where TPAP is also present. In NIH3T3 cells cotransfected with TPAP and GSG1, both proteins colocalize in the ER. Moreover, expression of GSG1 stimulates TPAP targeting to the ER, suggesting that interactions between the two proteins lead to the redistribution of TPAP from the cytosol to the ER.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Endoplasmic Reticulum / enzymology*
  • Humans
  • Immunohistochemistry
  • Immunoprecipitation
  • Male
  • Mice
  • Microscopy, Confocal
  • NIH 3T3 Cells
  • Polynucleotide Adenylyltransferase / metabolism*
  • Protein Binding
  • Protein Serine-Threonine Kinases / metabolism*
  • Testis / enzymology*


  • Protein Serine-Threonine Kinases
  • Polynucleotide Adenylyltransferase