Binding of mutant __SP__ __NODE__ protein ( C terminal truncation 171 End with its pleckstrin homology ( PH ) domain 1 and its pleckstrin homology ( PH ) domain 2 and its Syntrophin unique domain deleted N terminal truncation 1 74 with its pleckstrin homology ( PH ) domain 1 deleted and with its pdz domain retained ) and mutant __NODE__ protein ( N terminal truncation with its C terminal domain retained ) does not occur in a cell free system .