title: Origin of polyproline-rich peptides in human butyrylcholinesterase tetramers.
abstract: The human butyrylcholinesterase (HuBChE) tetramer is composed of 4 identical subunits and a noncovalently bound polyproline-rich peptide. In a previous report we identified lamellipodin as the source of the polyproline-rich peptides in HuBChE tetramers purified from plasma. Our current goal was to identify proteins in addition to lamellipodin that donate polyproline-rich peptides to plasma HuBChE tetramers. Peptides were released from 1 mg of pure plasma-derived HuBChE tetramers by boiling. Mass spectrometry identified 74 polyproline-rich peptides. MALDI-TOF mass spectra and spectral counting of the LC-MS/MS data supported the conclusion that lamellipodin accounted for 70% of the polyproline-rich peptides. Additional precursor proteins were matched through BLASTp searches, suggesting but not proving, that 20 proteins including UDP-N-acetyl glucosamine transferase ALG13 homolog, leiomodin 2, and zinc finger homeobox protein 2 are sources of polyproline-rich peptides found in HuBChE tetramers. Eighteen polyproline-rich peptides had no match in the human protein database. In conclusion, HuBChE assembles into tetramers through interaction of its C-terminal domain with polyproline peptides derived from a variety of proteins.
authors.affiliation: Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950, USA. Electronic address: hong.peng@unmc.edu.
authors.forename: Hong
authors.initials: H
authors.lastname: Peng
authors.affiliation: Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950, USA. Electronic address: lmschopf@unmc.edu.
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Schopfer
authors.affiliation: Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950, USA. Electronic address: olockrid@unmc.edu.
authors.forename: Oksana
authors.initials: O
authors.lastname: Lockridge
mesh_terms: D000595:Amino Acid Sequence; D002091:Butyrylcholinesterase / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D030562:Databases, Protein; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D010455:Peptides; D011498:Protein Precursors; C493339:RAPH1 protein, human; C011083:polyproline; D002091:Butyrylcholinesterase
keywords: Butyrylcholinesterase; Lamellipodin; Mass spectrometry; Polyproline; Tetramerization domain