Bacterially expressed murine CSF-1 possesses agonistic activity in its monomeric form.
CSF-1 is a dimeric peptide growth factor, stabilized by disulfide bonds. We expressed mouse CSF-1 in bacteria as a fusion protein either with glutathione S-transferase (GST) or with a six histidine tag (His-tag). Large amounts of recombinant material were obtained and purified by a single affinity chromatography step. Purified CSF-1-His-tag monomers efficiently dimerized in vitro, but the presence of variable amounts of GST-moiety in CSF-1 preparations obtained by thrombin cleavage of GST-fusion proteins (thrombin-released CSF-1) interfered with dimerization. However, the thrombin-released CSF-1 monomers possessed agonistic activity, being capable of stimulating tyrosine phosphorylation of the CSF-1 receptor and of an array of cellular proteins in living macrophages and of supporting their growth. These results show that CSF-1 dimerization is not essential for receptor activation in vivo.
Krautwald
S
S
Department of Immunbiology, Fraunhofer Institut for Toxicology and Molecular Biology, Hannover, Germany.
Baccarini
M
M
D000818:Animals; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D003001:Cloning, Molecular; D004220:Disulfides / Q000378:metabolism; D004926:Escherichia coli; D005982:Glutathione Transferase / Q000235:genetics; D006639:Histidine / Q000235:genetics; D016173:Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008264:Macrophages / Q000166:cytology; D051379:Mice; D017510:Protein Folding; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism
D004220:Disulfides; D011993:Recombinant Fusion Proteins; D006639:Histidine; D016173:Macrophage Colony-Stimulating Factor; D005982:Glutathione Transferase; D017479:Receptors, Platelet-Derived Growth Factor; D013917:Thrombin