Windows Defender-Startup Entry

I removed Windows Defender from the startup after disabling it. I want to put
the entry back into the registry key spo it will show up again in the startupo tab of msconfig
but I'm not sure where it resided.
I've re-enable it and in Servivces WD is set to Automatic but this did not
put the item back into the startup.
What is the path and the registry key that WD is in?