8 CONTROL MECHANISMS IN CELLULAR PROCESSES 



specific mutationally altered proteins formed as a consequence of 

 damage to different sites within the Tsase region? (3) Do the 

 CRM-less mutants represent a class of so-called "non-sense" muta- 

 tions in which information specifying a linking amino acid is absent? 

 If so, perhaps no molecule large enough, or of sufficiently similar 

 configuration to the enzyme, is synthesized which can be detected 

 either by its immunogenic or its antigenic properties. (4) Is there 

 any relationship between the type of CRM protein produced by the 

 mutant and the site or location of specific genetic damage within 

 the Tsase locus? 



As a result of detailed study of a number of Tsase mutants in 

 Neurospora and coli, several conclusions can be reached. ( 1 ) The 

 CRM's do actually represent genetically altered tryptophan synthe- 

 tase proteins. This conclusion is based on physical, enzymatic, and 

 immunochemical data (Suskind, 1957a; Suskind and Kurek, 1957; 

 Lerner and Yanofsky, 1957; Yanofsky and Stadler, 1958; De Moss 

 and Bonner, 1959; Mohler and Suskind, 1960; Carsiotis et al, 1960). 

 (2) The CRM's found in the various mutants are distinguishable 

 when a sufficient number of criteria are utilized for comparison ( Sus- 

 kind and Kurek, 1957; De Moss and Bonner, 1959; Yanofsky, 1960; 

 Suskind and Ligon, 1960). (3) There is some suggestion that one 

 CRM-less mutant may form some material related to Tsase. (4) It 

 appears that the location or site of genetic damage within certain 

 regions of the Tsase locus does determine the type of specific altered 

 protein which is formed, and that striking similarities are found be- 

 tween the organization of the Tsase genetic region in E. coli and in 

 N. crassa (Bonner et al, 1960; Yanofsky, 1960). 



Criteria which have been used to distinguish a number of dif- 

 ferent CRM proteins in E. coli and N. crassa Tsase mutants follow: 



1. Enzymatic activity and substrate-cof actor requirements 



2. Acid treatment 



3. Heat treatment 



4. Metal sensitivity 



5. Energy of activation 



6. Column chromatography and salt fractionation 



7. Immunogenic and antigenic properties 



8. Enzymatic activity/antigenic activity ratios 



9. Suppressor gene action 

 10. Complementation. 



