Fibroblast growth factor-1 interacts with the glucose-regulated protein GRP75/mortalin.
Fibroblast growth factor-1 (FGF-1), which lacks a signal peptide and is intracellularly localized as a result of endogenous expression or endocytosis, is thought to be involved in regulating cell growth and differentiation. In the study reported here, we purified proteins that bind intracellular FGF-1. Affinity adsorption was used to purify FGF-1-binding proteins from rat L6 cells expressing FGF-1. One of the isolated proteins was identified as the glucose-regulated protein GRP75/mortalin/PBP-74/mthsp70, a member of the hsp70 family of heat-shock proteins known to be involved in regulating glucose responses, antigen processing and cell mortality. The interaction of FGF-1 and GRP75/mortalin in vivo was confirmed by co-immunoprecipitation, immunohistochemical co-localization in Rat-1 fibroblasts and by using the yeast two-hybrid system. Moreover, a binding assay in vitro with the use of recombinant FGF-1 and mortalin demonstrated a direct physical interaction between the two proteins. These results reveal that GRP75/mortalin is an intracellular FGF-1-binding protein in cells and suggest that GRP75/mortalin is involved in the trafficking of and/or signalling by FGF-1.
Mizukoshi
E
E
Biosignaling Department, National Institute of Bioscience and Human Technology, Higashi 1-1,Tsukuba, Ibaraki 305-8566, Japan.
Suzuki
M
M
Loupatov
A
A
Uruno
T
T
Hayashi
H
H
Misono
T
T
Kaul
S C
SC
Wadhwa
R
R
Imamura
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins; D002460:Cell Line; D002846:Chromatography, Affinity; D016220:Fibroblast Growth Factor 1; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D024101:Mitochondrial Proteins; D008970:Molecular Weight; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D020539:Sequence Analysis, Protein; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; C492001:HSPA9 protein, human; C083794:Hspa9 protein, mouse; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins; C018551:glucose-regulated proteins; C080352:mortalin; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1