Identification of insulin-like growth factor-binding proteins in the circulation of four teleost fish species.
Insulin-like growth factor-binding proteins (IGF-BPs) were demonstrated in the circulation of four teleost fish species. In the coho salmon (Oncorhynchus kisutch), serum binding of 125I-labelled human IGF-I (125I-hIGF-I) was competitively inhibited by addition of excess recombinant bovine IGF-I (rbIGF-I) in a manner similar to that when rat serum was used. Western-ligand blot procedure using the same labelled hormone identified at least three major forms of IGF-BPs in the plasma of all four teleost species investigated: coho salmon, striped bass (Morone saxatilis), tilapia (Oreochromis mossambicus), and longjawed mudsucker (Gillichthys mirabilis). The first form is around 40-50 kDa, may be regulated by growth hormone (GH), and seems to be a good candidate for the fish version of mammalian IGF-BP3 (which is in the same size range and is GH-regulated). The second and third forms are 29 kDa and 31 kDa and are good candidates for the fish versions of mammalian IGF-BP1 and IGF-BP2, respectively, as they appear to be regulated by insulin and are in the same size range as their mammalian counterparts. Functionally different classes of circulating IGF-BPs may be conserved between fish and mammal.
Kelley
K M
KM
Department of Integrative Biology, University of California, Berkeley 94720.
Siharath
K
K
Bern
H A
HA
D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood*; D004591:Electrophoresis, Polyacrylamide Gel; D005399:Fishes / Q000097:blood*; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins