Answer: Nucleus membrane isn't part of the ER or Golgi Apparatus, BUT all of them are part of the endomembrane system.
Endoplasmic reticulum and Golgi apparatus are two membrane-bound organelles found in eukaryotes. Both these organelles are closely associated and functionally related. Both endoplasmic reticulum (ER) and Golgi apparatus are two components of the endomembrane system of a cell. Lysosomes and vesicals are the other components of the endomembrane system.