Cellular and sub-cellular expression of the GIMAPs

We have been keen to learn more about the intracellular location of GIMAP proteins. Some of them (notably GIMAP1 and GIMAP5) have protein regions which anchor them to membranes. Identifying in which sub-cellular membranes they are to be found could give important clues about their function.

From detailed studies we have drawn the unexpected conclusion that GIMAP5 is a lysosomal protein (Wong et al., 2010). By contrast, we found that GIMAP1 is located in the Golgi system of mouse lymphoid cells.

In the future, we will be interested to look for dynamic changes in the intracellular expression of GIMAP proteins during cellular responses to stimuli such as antigen-receptor activation, apoptosis induction and others (see below for new findings regarding GIMAP6).

GMAP1 expression
(L) GIMAP1 expressed in a mouse NKT cell line [C1498] is located in the Golgi apparatus.

Panel A – DAPI stain for DNA; Panel B – detection of giantin, a standard marker for the Golgi; Panel C – detection of endogenous GIMAP1 using a specific monoclonal antibody; Panel D – overlay of Panels A-C demonstrates substantial co-localisation of GIMAP1 with giantin

(R) Myc-tagged human GIMAP5 in stably transfected HEK293 cells detected in vesicular structures including lysosomes.