Binding of mutant __SP__ __NODE__ protein ( deletion 78 161 with its pdz domain deleted C terminal truncation 272 End with its pleckstrin homology ( PH ) domain 2 and its Syntrophin unique domain deleted and with its pleckstrin homology ( PH ) domain 1 retained ) and mutant __NODE__ protein ( N terminal truncation with its C terminal domain retained ) does not occur in a cell free system .