It controls protein synthesis, cell division and Nucleotide multiplication or formation (DNA or RNA) explicitly.
From the fore mentioned processes, protein synthesis is the most common and occurs on a regular basis to keep the cell function.
The nucleus is involved in the process of protein synthesis both internally and externally.
Even when medicine or anabolic steroid is used to enhance growth, the signal produced is processed by the nucleus to produce more protein. But the process needs to be understood more explicitly.
So How is the Nucleus Involved in Protein Synthesis
Three major roles include
- Host the machinery: of protein synthesis like DNA, messenger RNA (mRNA) formation, ribosomes, endoplasmic reticulum
- Receive the signal for protein synthesis
- Executing the protein synthesis.
But before we go into details, lets us see the major steps in protein synthesis.
a. Transcription of DNA produces a new mRNA which acts as a template for the formation of the new amino acid chain.
b. Formed mRNA moves out of nucleus and sites on rRNA in the rough endoplasmic reticulum attached to the nuclear membrane.
c. The ribosomes which are key sites for amino acid polymerization are produced in the nucleolus of the nucleus. The ribosomes exist as two sub-units as the 60S ribosome and 40S ribosomes. Once formed in the nucleolus, they come out of the nucleus through the nuclear pores present in the nuclear membrane. Then they sit on the rough endoplasmic reticulum in the cytoplasm.
tRNA brings the free amino acids from the cytoplasm on to the surface of mRNA now located on the nuclear membrane fixed on to the 60S ribosome in the endoplasmic reticulum.
Thus the key factors responsible for protein synthesis like the mRNA, ribosomes are formed inside the nucleus.
Besides this, the signal for protein synthesis is produced by few medicines and also by anabolic steroids. So this signaling pathway is transduced into the nucleus for the process to begin. So the entire protein synthesis happens inside and outside the surface of the nucleus.
Host the machinery: Nucleus is central to protein synthesis. All the molecules involved in the process of synthesis like the DNA, mRNA are present in the nucleus. Also the ribosomes, endoplasmic reticulum which aid in the protein synthesis is present over the surface of the nuclear membrane. Thus, the nucleus host the entire protein synthesis machinery. Once the amino-acid chains are formed, they can be dislodged from ribosomes to form proteins.
Receptors for signal: Drugs and anabolic steroids which induce protein synthesis, transmit their message to the nucleus through different receptors. The nuclear receptors receive this signal and produce the DNA to go for transcription which leads to the formation of mRNA.
Executing the protein synthesis: Once mRNA is formed by transcription, it comes out of the nuclear membrane. Immediately outside the nuclear membrane, it binds to ribosomes especially the larger sub=unit (60s ribosome). On the ribosome’s translation of mRNA to form an amino-acid chain takes place. The smaller subunit of ribosomes (the 40s (helps in reading the mRNA. The amino acids from the cytoplasm are brought on to the mRNA fixed on to the ribosome. These amino acids are carried by tRNA (transfer RNA) and allowed to link to each other.