7. THE ULTIMOBRANCHIAL GLANDS
389
Table II
Amino Acid Composition of Calcitonin
Pig'
Salmon*
Residues
(thyroid)
(ultimobranchial)
Alanine
1
0
Arginine
2
1
Aspartic (asparagine)
4
2
Cysteine
2
2
Glutamic acid
1
3
Glycine
3
3
Histidine
1
1
Isoleucine
0
0
Leucine
3
5
Lysine
0
2
Methionine
1
0
Phenylalanine
3
0
Proline
2
2
Serine
4
4
Threonine
2
5
Tryptophan
1
0
Tyrosine
1
1
Valine
1
1
Total
32
Molecular weight
3605
Biological activity
200 U/mg
32
3427
5000 U /mg
Potta el al. (1968).
* O'Dor et al. (1969b).
salmon calcitonin is approximately 5OOO MRC (Medical Research Council) units per mg, or 25 times that of porcine hormone. It also has a much
more prolonged effect when injected into rats and rabbits (Brooks et al.,
1969). Its structure is shown in Fig. 6.
D. Distribution in Vertebrates
As shown in Table 111, calcitonin has been extracted from thyroid and
parathyroid glands of mammals, and from ultimobranchial glands of
representatives of all other classes of jawed vertebrates (Copp and Parkes,
1968). The ultimobranchial material collected from the dogfish shark,
chum salmon, and gray cod contained considerable extraneous connective
tissue so that the actual concentration may be comparable to that in
chicken and turkey glands and is, of course, far higher than that in mam-