Question

Through which of the following are the ribosomes attached to endoplasmic reticulum?
A. rRNA
B. mRNA
C. Ribophorins
D. All of the above

Answer 1

Hint: Ribophorin are ribosome receptor proteins. They are dome shaped transmembrane glycoproteins which are located in the membrane of the rough ER (endoplasmic reticulum).

Complete Answer:
Ribosomes are present in many regions around a eukaryotic cell. Endoplasmic reticulum with linked ribosomes is called rough ER. It looks bumpy under a microscope. The connected ribosomes produce proteins that will be utilized inside of the cell and proteins produced for carry out of the cell. A few ribosomes are linked to the nuclear envelope. Those ribosomes synthesize proteins that are secreted into the perinuclear space.

Now, let us find the solution from the option.
- rRNAs are present in the ribosomes and account for 80% of the total RNA present in the cell.
- Messenger RNA is a type of RNA molecule which is complementing the one of DNA strands present in a gene.
- Membranes of endoplasmic reticulum carry ribosomes when ER is known as rough endoplasmic reticulum. These cells are involved in active secretion.
- Connection between ribosome and endoplasmic reticulum is via 'signal recognition particle' attached to a 60S subunit of ribosome and ribophorin or SRP receptor located around the ER.

Thus, the correct option is D. i.e. Ribophorins.

Note: Rough ER is a keeper for ribosomes that constantly link to and separate from the ER surface. Importantly, the endoplasmic reticulum and ribosomes function together in manner to produce proteins and have them carried to their final location. The rough ER’s major role is to support structure and store proteins, whilst the smooth ER store lipids which are a kind of fat.