title: Proteomics shows Hsp70 does not bind peptide sequences indiscriminately in vivo.
abstract: Heat shock protein 70 (Hsp70) binds peptide and has several functions that include protein folding, protein trafficking, and involvement with immune function. However, endogenous Hsp70-binding peptides had not previously been identified. Therefore, we eluted and identified several hundred endogenously bound peptides from Hsp70 using liquid chromatography ion trap mass spectrophotometry (LC-ITMS). Our work shows that the peptides are capable of binding Hsp70 as previously described. They are generally 8-26 amino acids in length and correspond to specific regions of many proteins. Through computationally assisted analysis of peptides eluted from Hsp70 we determined variable amino acid sequences, including a 5 amino acid core sequence that Hsp70 favorably binds. We also developed a computer algorithm that predicts Hsp70 binding within proteins. This work helps to define what peptides are bound by Hsp70 in vivo and suggests that Hsp70 facilitates peptide selection by aiding a funneling mechanism that is flexible but allows only a limited number of peptides to be processed.
authors.affiliation: Department of Biochemistry/Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Grossmann
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Madden
authors.forename: Fan
authors.initials: F
authors.lastname: Gao
authors.forename: Yuan-Ping
authors.initials: YP
authors.lastname: Pang
authors.forename: John E
authors.initials: JE
authors.lastname: Carpenter
authors.forename: Daniel
authors.initials: D
authors.lastname: McCormick
authors.forename: Charles Y F
authors.initials: CY
authors.lastname: Young
mesh_terms: D000465:Algorithms; D020816:Amino Acid Motifs / Q000502:physiology*; D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002460:Cell Line; D002853:Chromatography, Liquid; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D051379:Mice; D008958:Models, Molecular; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D040901:Proteomics / Q000379:methods*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D010455:Peptides