A membrane fraction (SN 4), prepared from developing and mature rat forebrain by hypo-osmotic treatment of microsome (microsomal-fraction)-free myelin, appears to be closely related to the myelin-like fraction. Fraction SN 4 shows 2′:3′-cyclic nucleotide 3′-phosphohydrolase activity higher than that of the parent myelin. Electrophoresis reveals a multitude of bands with the Wolfgram protein as the main component.
