well i dont know if i answer ur question or not but some things should be kept in mind regarding GUIs in matlab
1. U cannot run the matlab file made on higeher version on lower versions, i.e. file made in matlab 7 will not run in matlab6 or lower versions.
2. to run GUI u need not to have Matlab installed but there is GUI tool which should be installed in the pc. ( i forgot the package name but its comes along with matlab and is installed by defult when installing the matlab)
3. Some time there is not only one file for running GUI, u may have called functions in the code of GUI.