title: Asteropsin A: an unusual cystine-crosslinked peptide from porifera enhances neuronal Ca2+ influx.
abstract: BACKGROUND
  Herein we report the discovery of a cystine-crosslinked peptide from Porifera along with high-quality spatial details accompanied by the description of its unique effect on neuronal calcium influx.
  
  
  METHODS
  Asteropsin A (ASPA) was isolated from the marine sponge Asteropus sp., and its structure was independently determined using X-ray crystallography (0.87 angstroms) and solution NMR spectroscopy.
  
  
  RESULTS
  An N-terminal pyroglutamate modification, uncommon cis proline conformations, and absence of basic residues helped distinguish ASPA from other cystine-crosslinked knot peptides. ASPA enhanced Ca2+ influx in murine cerebrocortical neuron cells following the addition of the Na+ channel activator veratridine but did not modify the oscillation frequency or amplitude of neuronal Ca2+ currents alone. Allosterism at neurotoxin site 2 was not observed, suggesting an alternative to the known Na+ channel interaction.
  
  
  CONCLUSIONS
  Together with a distinct biological activity, the origin of ASPA suggests a new subclass of cystine-rich knot peptides associated with Porifera.
  
  
  CONCLUSIONS
  The discovery of ASPA represents a distinctive addition to an emerging subclass of cystine-crosslinked knot peptides from Porifera.
authors.affiliation: College of Pharmacy, Pusan National University, Busan 609-735, Korea. lihuayue@naver.com
authors.forename: Huayue
authors.initials: H
authors.lastname: Li
authors.forename: John J
authors.initials: JJ
authors.lastname: Bowling
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek
authors.forename: Jongki
authors.initials: J
authors.lastname: Hong
authors.forename: Sairam V
authors.initials: SV
authors.lastname: Jabba
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Murray
authors.forename: Nam-Chul
authors.initials: NC
authors.lastname: Ha
authors.forename: Mark T
authors.initials: MT
authors.lastname: Hamann
authors.forename: Jee H
authors.initials: JH
authors.lastname: Jung
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018360:Crystallography, X-Ray; D003553:Cystine / Q000737:chemistry*; D017136:Ion Transport / Q000187:drug effects; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D011161:Porifera / Q000737:chemistry*; D061251:Primary Cell Culture; D011487:Protein Conformation; D017510:Protein Folding; D015222:Sodium Channels / Q000378:metabolism; D014701:Veratridine / Q000494:pharmacology
chemical_list: D010455:Peptides; D015222:Sodium Channels; C581719:asteropsin A; D003553:Cystine; D014701:Veratridine; D002118:Calcium