Binding of mutant __SP__ __NODE__ protein ( C terminal truncation 407 End with its Syntrophin unique domain deleted and with its pleckstrin homology ( PH ) domain 2 retained N terminal truncation 1 280 with its pdz domain and its pleckstrin homology ( PH ) domain 1 deleted ) and mutant __NODE__ protein ( N terminal truncation with its C terminal domain retained ) does not occur in a cell free system .