Title : Structural characterization of recombinant soluble rat
neuroligin 1 : mapping of secondary structure and glycosylation by mass spectrometry
Abstract :
- Neuroligins (NLs) are a family of transmembrane proteins that function in synapse formation and/or remodeling by interacting with beta-neurexins (beta-NXs) to form heterophilic cell adhesions
- The large N-terminal extracellular domain of NLs, required for beta-NX interactions, has sequence homology to the alpha/beta hydrolase fold superfamily of proteins
- By peptide mapping and mass spectrometric analysis of a soluble recombinant form of NL1, several structural features of the extracellular domain have been established
- Of the nine cysteine residues in NL1, eight are shown to form intramolecular disulfide bonds
- Disulfide pairings of Cys 117 to Cys 153 and Cys 342 to Cys 353 are consistent with disulfide linkages that are conserved among the family of alpha/beta hydrolase proteins
- The disulfide bond between Cys 172 and Cys 181 occurs within a region of the protein encoded by an alternatively spliced exon
- The disulfide pairing of Cys 512 and Cys 546 in NL1 yields a structural motif unique to the NLs, since these residues are highly conserved
- The potential N-glycosylation sequons in NL1 at Asn 109, Asn 303, Asn 343, and Asn 547 are shown occupied by carbohydrate
- An additional consensus sequence for N-glycosylation at Asn 662 is likely occupied
- Analysis of N-linked oligosaccharide content by mass matching paradigms reveals significant microheterogeneous populations of complex glycosyl moieties
- In addition, O-linked glycosylation is observed in the predicted stalk region of NL1, prior to the transmembrane spanning domain
- From predictions based on sequence homology of NL1 to acetylcholinesterase and the molecular features of NL1 established from mass spectrometric analysis, a novel topology model for NL three-dimensional structure has been constructed
Output (sent_index, trigger,
protein,
sugar,
site):
- 11. glycosylation, , -, -, region
- 8. N-glycosylation, , -, -, -
- 8. occupied, , -, -, Asn 109, Asn 303, Asn 343, and Asn 547
- 9. occupied, , -, -, Asn 662
- 9. occupied, , -, -, sequence
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 8. neuroligin 1, -, Asn 109, Asn 303, Asn 343, and Asn 547
- 9. neuroligin 1, -, Asn 662