Question

What is ribophorin?

Answer 1

Hint: There are kinds of glycoproteins or ribosome receptor proteins that are not present in the membrane of smooth endoplasmic reticulum but are found in the rough endoplasmic reticulum. These proteins have good preservation, great abundance and importance in the reticulum.

Complete answer:
Ribophorin is the ribosome receptor protein or the transmembrane glycoprotein which has a dome-like shape which is not present in the smooth endoplasmic reticulum but is situated in the rough endoplasmic reticulum. Ribophorin is responsible for assisting the 60S subunit of the eukaryotic ribosome to bind to the rough endoplasmic reticulum. There are two types of Ribophorin which are classified into Ribophorin I and Ribophorin II. Both types of Ribophorin are only found in eukaryotic cells. Both the types of ribophorin act as two different subunits in the protein complex oligosaccharyltransferase (OST).

Functions of Ribophorin I and Ribophorin
> Both the transmembrane glycoprotein of the rough endoplasmic reticulum i.e Ribophorin I & II intervene in the combination of the ribosomes as they fix the 60S (large subunit) of the ribosome.
> They play a significant role in the co-translational translocation methods which are based on the union by either transferring them to the lumen of the cistern or the nascent polypeptide is inserted to the membrane.


Note:
Sub-kingdom Cryptogams include three divisions namely Thallophyta, Bryophyta, and Pteridophyta. Division -Thallophyta includes algae. Division -Bryophyta includes mosses whereas division – Pteridophyta includes ferns. Cryptogams are lower plants that do not have developed vascular tissues like xylem and phloem. Also, the plant body is not differentiated into root, stem, and leaves.
On the contrary, Phanerogams are plants that have seeds and are also called spermatophytes. The plant body in phanerogams is differentiated into root, stem, and leaves. They have a very well developed vascular system.