Identification of a peptide fragment from the carboxyl-terminal extension region (E-domain) of rat proinsulin-like growth factor-II.
A fragment of the carboxyl-terminal extension region (E-peptide) of rat proinsulin-like growth factor-II has been purified from medium conditioned by cultured BRL-3A rat liver cells. The fragment, identified by microsequence analysis, was discovered in a biologically active fraction of insulin-like growth factor II (IGF-II). The fragment begins at position 117 in pro-IGF-II, two amino acids downstream from an Arg-Arg potential prohormone processing site. A synthetic analogue of the E-peptide at high concentrations stimulates [3H]thymidine incorporation in NIL8 hamster cells, raising the possibility that the E-peptide might bind with low affinity to a mitogen receptor. Peptides from the E-regions of pro-IGF-I and pro-IGF-II should be useful for development of radioimmunoassays for measurement of the somatic production of IGF-I and IGF-II, analogous to the radioimmunoassay for the insulin C-peptide.
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003470:Culture Media; D004261:DNA Replication / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000302:isolation & purification* / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification* / Q000494:pharmacology; D051381:Rats; D013002:Somatomedins / Q000302:isolation & purification*
D003470:Culture Media; D010446:Peptide Fragments; D013002:Somatomedins; D007335:Insulin-Like Growth Factor II