Binding of insulin-like growth factor-I (IGF-I) to primary cultures of chondrocytes from rat rib growth cartilage.
Binding of insulin-like growth factor I (IGF-I) to cultured resting, proliferative and hypertrophic growth plate chondrocytes was investigated. The optimal binding conditions and the extent of degradation of the 125I-IGF-I at 20 degrees C were analyzed in a time-course study. The maximal binding without noticeable degradation was observed after 3 h. The binding of IGF-I to the proliferative cells was 2-fold higher than to the resting and the hypertrophic cells. On the proliferative chondrocytes two classes of receptors with different affinities were found. 125I-IGF-I could be displaced from the proliferative cells by unlabelled IGF-I, IGF-II and insulin, respectively. Half maximal binding was observed at 0.3 nmol/l (= 2.2 micrograms/l) of IGF-I, 4.3 nmol/l (= 32 micrograms/l) of IGF-II and 350 nmol/l (= 2000 micrograms/l) of insulin. No specific binding of human growth hormone (hGH) could be demonstrated. When binding of epidermal growth factor (EGF) to the proliferative cells was assessed, little, but specific binding was observed.
Makower
A M
AM
Department of Medical Cell Biology, Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden.
Skottner
A
A
Wroblewski
J
J
D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000378:metabolism*; D002455:Cell Division; D004815:Epidermal Growth Factor / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism; D006132:Growth Plate / Q000166:cytology / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000378:metabolism*
D013002:Somatomedins; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone