Page 61 - Cell biology PDG 2024

The 19S regulatory units control the opening and closing of the gates into
the 20S catalytic barrel.
A polyubiquitinated protein is first bound to the 19S regulatory unit in an
ATP-dependent reaction (the 19S contains ATPase activity). 19S unit
opens the gates of the 20S unit, possibly involving ATP hydrolysis, and
guides the protein into the central proteolytic chamber. The proteasomes
has threonine protease activity that cuts most proteins into regular 8-9
residue polypeptides.

Figure 28: proteosome structure

By the end of this chapter the student should know:
1) Describe the molecular structure and function of the essential
biomolecules (proteins).
2) Recall the structure and function of nucleotides & nucleic acids
and appreciate their role in protein synthesis and inheritance.
3) Comprehend the biochemical basis of drug action in view of
structure and function of basic macromolecules present in our bodies
4) Analyze and interpret the biochemical data obtained in the
practical sessions.

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