X. TMV STUDIES IN GENETIC CODING 



515 



Pro 



2 (7) 



-»- Leu 



Tyr 



AU, (O) 



A<U (N) 



3 (1) 



t 

 -Phe 



U3(N,0) 



(1) 



Asp 



lieu 



(AspN) 

 (Asp) 



A2U (O) 

 CAU 

 GAU (O) 



T2 

 Ala 



AU2 (O) 

 A,-U,(N) 



rCGU(N,0)1 



Glu 



AGU (O) 

 CGU (N) 



Arg- 



2^(2) 



CGU(N,0) 



Fig. 8. Correlation of observed amino acid replacements with coding symbols. 

 All amino acid exchanges that have been observed in this laboratory are shown, with 

 their frequency of occurrence. Numbers in parenthesis indicate exchanges resulting 

 from reactions other than deamination, and thus unrelated to the arrangement 

 scheme of this presentation which is based on the decreasing cytosine content from 

 left to right. Solid lines and underlined code s>'mbols indicate agreement of amino 

 acid exchange data with C -^ U transformations. "N" and "O" after the code 

 symbols refers to the origin of the respective identification, "N" standing for 

 Nirenberg and Matthaei (1961), Nirenberg et al. (1962), and Martin et al. (1962), 

 and "O" standing for Lengyel et al., 1961, 1962. and Speyer et al. (1962). The 

 symbol 2* in the bottom line refers to the fact that a progeny isolate of this strain 

 showed three arginines to be replaced by glj^cines, rather than two. 



