Shell Programming and Scripting

I have the following line an in input file I want to digest with sed and simple replace the bold part with a variable defined in my bash script. I can do this in several sed operations but I know there must be a way to do it in a single sed line. What is the syntax?

Line in file:
_kernver="$(cat /lib/modules/${_extramodules}/version)"

I wish to clip the bolded stuff and replace it like so:
_kernver="$new"

---------- Post updated at 05:09 PM ---------- Previous update was at 04:56 PM ----------

Nevermind... think I got it on my own (gotta love trial and error):

sed "/_kernver/ s,=.*$,=\"$new\"," file

Code:

echo '_kernver="$(cat /lib/modules/${_extramodules}/version)"' | sed "/^_kernver=/s#=.*#=\"\$new\"#"