What Is a Free Ribosome?

Ribosome, formerly known as "ribosome" or "ribosome", is generally considered to be a type of organelle in cells. Except for mature mammalian red blood cells and plant sieve cells, ribosomes are found in cells. presence. Generally speaking, prokaryotic cells have only one type of ribosome, while eukaryotic cells have two types of ribosome (wherein ribosomes in mitochondria are not the same as cytoplasmic ribosomes).

Ribosome

Ribosome, formerly known as "

Ribosome is a kind of intracellular

The ribosome is a highly complex cellular machine. It mainly consists of

Although the ribosomes vary greatly in size, their core structures are very similar. Most rRNAs are highly organized into various tertiary structure motifs. The extra RNA in the larger ribosome appears as several long consecutive insertions, allowing them to form a loop in the core structure without being destroyed or altered ^[3]

The general molecular structure of the ribosome was resolved in the early 1970s. At the beginning of the 21st century, the ribosome structure has been resolved with high resolution to an accuracy of about a few nm.

In 2000, the paleontological Haloarcula marismortui ^[17]

Bacterial cells synthesize ribosomes in the cytoplasm through the transcription of multiple ribosome gene operons. In eukaryotes, this synthesis occurs in the cytoplasm and nucleoli, and the assembly process involves the coordination of more than 200 proteins in four types of rRNA synthesis, processing, and assembly.

The ribosome may have originated from RNA in the first place, and looks like a self-replicating complex, which only evolved to synthesize proteins after the emergence of amino acids. The driving force behind the evolution of the ribosome from the ancient self-replicating machine to its current form of translation machine may be the selective pressure of binding proteins to the self-replicating mechanism of the ribosome, a transformation that increases its ability to self-replicate ^[25]

Generally speaking, there are only two types of ribosomes: prokaryotic and eukaryotic. But ribosomes

A group of highly acidic ribosomal proteins (RP), also known as P proteins, exist in multiple copies on the 60S subunit in the ribosome stem, and P proteins mediate selective translation ^[29] . These P proteins can be found in yeast and mammalian cells. If there is no P protein in the yeast, the yeast is sensitive to cold. If human cells lack P protein, they induce autophagy ^[30] .

Some ribosomal proteins are absolutely critical, while others are not. For example, in mice, Rpl38 is required for Hox mRNA subgroup translation, and mutations in Rpl38 result in short-tailed homeotropic transformation ^[31] .

Modifications of the core ribosomal protein (RP) can also cause the formation of heterogeneous ribosomes.