<P> The membrane of the rough endoplasmic reticulum forms large double membrane sheets that are located near , and continuous with , the outer layer of the nuclear envelope . The double membrane sheets are stacked and connected through several right or left - handed helical ramps , the so - called Terasaki ramps , giving rise to a structure resembling a multi-storey car park . Although there is no continuous membrane between the endoplasmic reticulum and the Golgi apparatus , membrane - bound transport vesicles shuttle proteins between these two compartments . Vesicles are surrounded by coating proteins called COPI and COPII . COPII targets vesicles to the Golgi apparatus and COPI marks them to be brought back to the rough endoplasmic reticulum . The rough endoplasmic reticulum works in concert with the Golgi complex to target new proteins to their proper destinations . A second method of transport out of the endoplasmic reticulum involves areas called membrane contact sites , where the membranes of the endoplasmic reticulum and other organelles are held closely together , allowing the transfer of lipids and other small molecules . </P>
<P> The membrane of the rough endoplasmic reticulum forms large double membrane sheets that are located near , and continuous with , the outer layer of the nuclear envelope . The double membrane sheets are stacked and connected through several right or left - handed helical ramps , the so - called Terasaki ramps , giving rise to a structure resembling a multi-storey car park . Although there is no continuous membrane between the endoplasmic reticulum and the Golgi apparatus , membrane - bound transport vesicles shuttle proteins between these two compartments . Vesicles are surrounded by coating proteins called COPI and COPII . COPII targets vesicles to the Golgi apparatus and COPI marks them to be brought back to the rough endoplasmic reticulum . The rough endoplasmic reticulum works in concert with the Golgi complex to target new proteins to their proper destinations . A second method of transport out of the endoplasmic reticulum involves areas called membrane contact sites , where the membranes of the endoplasmic reticulum and other organelles are held closely together , allowing the transfer of lipids and other small molecules . </P>
where is the rough er located in a cell
where is the rough er located in a cell
near , and continuous with , the outer layer of the nuclear envelope
near , and continuous with , the outer layer of the nuclear envelope