LEWIS ET AL. : GROWTH HORMONE- AND PROLACTIN-LIKE PROTEINS 



GEL CONCENTRATION (%) 



Figure 5. — Immunodiffusion plate for the S and F pro- 

 teins. Antiserum to mouse growth hormone (10 /iliter) 

 was in the center well of A and B; antiserum to mouse 

 prolactin was in the center well of C. The outer wells 

 of A contained: 1, 10 /xg component S; 2 and 5, 5 /ig 

 mouse growth hormone; 3, 5 fig component S; 5, 2 /xg 

 component F. The outer wells of C contained: 1, 10 /ig 

 component S; 2, 5 fig mouse prolactin; 3, 10 fig com- 

 ponent F; 4, 5 fig mouse prolactin. The picture was 

 taken after 24 hr at room temperature. 



Figure 4. — A Ferguson plot of the relative mobility 

 (Rm) of the S and F components and their altered 

 forms (S' and F') versus the concentration of acryla- 

 mide used for the gel-electrophoresis. 



The molecular weights of the other electro- 

 phoretic components seen in Figure 3 were A = 

 68,000; B = 65,000; C = 60,000; D = 47,000; 

 E = 71,000; G = 64,000; H = 72,000. 



IMMUNODIFFUSION 



The purified preparations of S and F, which 

 also contained S' and F', respectively, produced 

 a precipitin line when tested against antiserum 

 to mouse growth hormone (Figure 5). When 

 tested at the same concentration, S gave a more 

 pronounced line than did F. Neither prepara- 

 tion gave a precipitin line with antiserum to 

 mouse prolactin. 



Table 1. — Amino acid composition of performic acid 

 oxidized components S and F. 



Amino acid 



Component S 

 residues! 



Component F 

 residues' 



1 Based on 22,000 daltons for S and 20,000 for F. 

 ^ Spectrophotomefric (Beaven and Holiday, 1952). 



AMINO ACID COMPOSITION 



Table 1 gives the amino acid analyses of com- 

 ponents S and F. The composition of the two 

 proteins was quite similar but there were definite 

 differences and component S had a greater total 

 number of amino acids. Both contained six half- 

 cystines and two tryptophans. 



PEPTIDE MAPS 



Figure 6 is a drawing of the peptide map ob- 

 tained with component S. The F component 

 gave an almost identical map but was different 

 in that peptides labeled S were not seen and an- 

 other peptide labeled F was noted. 



937 



