20 



Inside the Living Cell 



phe 



I 



val 



I 

 asp 



I 



glu 



I 



his 



I 



leu 



I 



cys 



I 

 glu 



I 

 ser 



I 



his 



I 



leu 



val 

 I 



glu 



I 

 ala 



I 

 leu 



I 

 tyr 



I 

 leu 



I 

 val 



I 

 cys ■ 



I 



I 



glu 



I 



arg 

 I 



g'y 

 I 



phe 



I 

 phe 



I 

 tyr 



I 

 thr 



I 

 pro 



I 

 hys 



I 

 ala 



— S S — 



\ 



S — 



g'y 

 I 



lieu 



I 

 val 



glu 



I 



glu 



I 



cys 



I 

 cys 



I 

 thr 



I 

 ser 



I 



lieu 



I 

 cys 



I 

 ser 



I 

 leu 



I 

 tyr 



I 

 glu- 



I 

 leu 



I 

 glu 



I 

 asp' 



I 

 tyr 



I 



cys 



I 

 asp- 



NH2 



S 



I 



S 



B 



NH2 



NH- 



•NH- 



Variants in position B 



Cattle 



ala 

 I 



g'y 

 I 



val 



Sheep 



ala 



I 

 ser 



I 

 val 



FIG. 3. The arrangement of the fifty-one amino acids in the molecule of pig 

 insulin (for full names, see Appendix, p. 162). Insulins from other species 

 differ slightly in the short section marked B. asp — NH2 is asparigine and 

 glu — ^NH2 is glutamine. 



