Prefoldin-nascent chain complexes in the folding of cytoskeletal proteins.
In vitro transcription/translation of actin cDNA and analysis of the translation products by native-PAGE was used to study the maturation pathway of actin. During the course of actin synthesis, several distinct actin-containing species were observed and the composition of each determined by immunological procedures. After synthesis of the first approximately 145 amino acids, the nascent ribosome-associated actin chain binds to the recently identified heteromeric chaperone protein, prefoldin (PFD). PFD remains bound to the relatively unfolded actin polypeptide until its posttranslational delivery to cytosolic chaperonin (CCT). We show that alpha- and beta-tubulin follow a similar maturation pathway, but to date find no evidence for an interaction between PFD and several noncytoskeletal proteins. We conclude that PFD functions by selectively targeting nascent actin and tubulin chains pending their transfer to CCT for final folding and/or assembly.
Hansen
W J
WJ
Surgical Research Laboratory, San Francisco General Hospital, Departments of Surgery, Medicine, and Physiology, University of California, San Francisco, California 94143, USA. hanswb@itsa.ucsf.edu
Cowan
N J
NJ
Welch
W J
WJ
D000199:Actins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000818:Animals; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D014158:Transcription, Genetic; D014404:Tubulin / Q000096:biosynthesis / Q000737:chemistry
D000199:Actins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D005656:Fungal Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D014404:Tubulin; C112806:prefoldin