RNA IN THE SYNTHESIS OF PROTEINS 



or is cnzymatically degraded. If so, this important decision is settled by a 

 chance event unrelated to the biological need for specific messengers. 



Conclusion 



We can now have considerable confidence that the broad features of protein 

 synthesis are understood. RN A's involvement is very much more complicated 

 than imagined in 1953. There is not one functional RNA. Instead, protein 

 synthesis demands the ordered interaction of three classes of RNA - ribo- 

 somal, soluble, and messenger. Many important aspects, however, remain 

 unanswered. For instance, there is no theoretical framework for the riboso- 

 mal sub-units nor, for that matter, do we understand the functional signif- 

 icance of ribosomal RNA. Most satisfying is the realization that all the steps 

 in protein replication will be shown to involve well-understood chemical 

 forces. As yet we do not know all the details. For example, are the DNA 

 base-pairs involved in messenger RNA selection of the corresponding amino- 

 acyl-sRNA? With luck, this will soon be known. We should thus have 

 every expectation that future progress in understanding selective protein 

 synthesis (and its consequences for embryology) will have a similar well- 

 defined and, when understood, easy-to-comprchend chemical basis. 



Acknowledgment 



I have been very fortunate in having the collaboration of many able students 

 and colleagues. The Ph.D. thesis work of Dr. C. G. Kurland, Dr. David 

 Schlessingcr and Dr. Robert Riscbrough established many ideas reported 

 here. Equally significant have been experiments by Drs. Kimiko Asano, 

 Michael Cannon, Walter Gilbert, Francois Gros, Francoisc Gros, Johns 

 Hopkins, Masayasu Nomura, Pierre Francois Spahr, Alfred Tissiercs, and 

 Jean-Pierre Waller. The visit of Francois Gros in the spring of i960 was 

 crucial in focusing attention on messenger RNA. Most importantly, I wish 

 to mention my lengthy and still continuing successful collaboration with 

 Alfred Tissieres. Since i960, I have the good fortune to also work closely 

 with Walter Gilbert. 



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