M. Nakamura et al., IDENTIFICATION OF PROTEIN-C IN SERA OF THE FROGS, RANA-NIGROMACULATA AND RANA-BREVIPODA, Zoological science, 11(5), 1994, pp. 763-766
When sera from the frogs, Rana (R.) nigromaculata and Rana (R.) brevip
oda, were run on starch-gel electrophoresis (SGE), several bands were
seen in an electrophoretic pattern of proteins. This pattern on SGE ap
peared the same at stages XIV, XV and XXI, and in the adult frog, R. n
iguromaculata. However, the pattern at stage X was different. A protei
n, designated ''protein C'', did not appear clearly at this stage, but
afterwards. This protein was the second richest among serum proteins
of mature frogs. Protein C (Mr=180 kD, when estimated by SDS-PAGE) was
obtained after SGE and then subjected to an NH2-terminal sequence ana
lysis. Sequences of protein C from R. nigromaculata and R. brevipoda w
ere NH2-TDPMYVIFIPQTLXE for the first 15 amino acids and NH2-TDPHYVIFK
G for the first 10 amino acids, respectively. Homology search of GenBa
nk sequences indicated no significant similarity with any known protei
ns. The results suggest that protein C is a new protein, and that it m
ay play an important role(s) in the serum after stage X in these speci
es.