The Ubiquitin System for Protein Degradation and Some of Its Roles in the Control of the Cell-Division Cycle

摘要

All living cells contain many thousands of different proteins,each of which carries out a specific chemical or physical process.Due to the importance of proteins in basic cellular functions,there has been a great interest in the problem of how proteins are synthesized.In the fifties and sixties of the 20th century,the discovery of the double-helical structure of DNA and the cracking of the genetic code focused attention on the mechanisms by which the order of bases in DNA determines the sequence of amino acids in proteins,and on further molecular mechanisms that regulate the expression of specific genes.