I found the executable file and some related files in /usr/bin. It is named gnome-screenshot --interactive. However, I still cannot find anything in synaptic even close to that; either installed or not. I am suspicious that it was loaded as part of gnome.
My main concern is one of possible conflict between "Take Screenshot" and "Shutter" and/or unnecessary use of memory. "Take Screenshot currently loads into memory at startup and the prtscn key activates it. I can set "Shutter" to be activated by the prtscn key and when I do so, "Take Screenshot" no longer is. However, I assume both are then loaded into memory. I can't find any preference settings for "Take Screenshot" or any configuration files for it. Running the command "gnome-screenshot --help" in a terminal lists a number of options, but none provide a way to deactivate it.
Maybe my concern is unfounded. When activating "shutter" with prtscn, it appears to work properly and no smoke or anything comes from the computer