Nepl19 is a secreted neprilysin-like M13-family protein. It retains the peptidase-like architecture but replaces essential residues in the conserved catalytic zinc-binding motif, supporting a noncatalytic pseudopeptidase identity. Its physiological ligand and biological role remain unknown; peptide binding or modulation of extracellular peptide availability are possibilities rather than established functions.
Summary: Nepl19 has a cleavable signal peptide and lacks a retained membrane-spanning anchor. The systematic fly-family analysis distinguishes secreted Nepl proteins from conventional membrane-bound neprilysins. Extracellular region is the appropriate inferred compartment; the membrane-tethered ancestral localization is not conserved in this target.
Reason: Nepl19 has a cleavable signal peptide and lacks a retained membrane-spanning anchor. The systematic fly-family analysis distinguishes secreted Nepl proteins from conventional membrane-bound neprilysins. Extracellular region is the appropriate inferred compartment; the membrane-tethered ancestral localization is not conserved in this target.
The selected UniProt sequence has a SignalP-derived signal peptide at 1–24 and a mature chain at 25–671, with no annotated transmembrane segment. The mature C-terminal sequence ends in TSPQKCQLFAVNLD, lacking a hydrophobic membrane anchor.
two Nep and the majority (18) of Nepl proteins lack a predicted transmembrane domain and, instead, possess a predicted signal peptide suggesting that they are secreted
Summary: Nepl19 has a cleavable signal peptide and lacks a retained membrane-spanning anchor. The systematic fly-family analysis distinguishes secreted Nepl proteins from conventional membrane-bound neprilysins. Extracellular region is the appropriate inferred compartment; the membrane-tethered ancestral localization is not conserved in this target.
Reason: Nepl19 has a cleavable signal peptide and lacks a retained membrane-spanning anchor. The systematic fly-family analysis distinguishes secreted Nepl proteins from conventional membrane-bound neprilysins. Extracellular region is the appropriate inferred compartment; the membrane-tethered ancestral localization is not conserved in this target.
The selected UniProt sequence has a SignalP-derived signal peptide at 1–24 and a mature chain at 25–671, with no annotated transmembrane segment. The mature C-terminal sequence ends in TSPQKCQLFAVNLD, lacking a hydrophobic membrane anchor.
two Nep and the majority (18) of Nepl proteins lack a predicted transmembrane domain and, instead, possess a predicted signal peptide suggesting that they are secreted
Summary: Intrinsic conventional neprilysin catalysis is contradicted by loss of essential residues. Participation in proteolysis could nevertheless occur through noncatalytic peptide binding or regulation, but that role is not established for Nepl19. Preserve the process unresolved rather than infer either participation or exclusion solely from catalytic loss.
Reason: Intrinsic conventional neprilysin catalysis is contradicted by loss of essential residues. Participation in proteolysis could nevertheless occur through noncatalytic peptide binding or regulation, but that role is not established for Nepl19. Preserve the process unresolved rather than infer either participation or exclusion solely from catalytic loss.
The reference HEITH motif at 584–588 maps to QQLAH at Nepl19 511–515. Nepl19 retains the M13 fold and downstream ENIAD region but replaces the first zinc-binding histidine and catalytic glutamate with glutamines.
The 21 Nepl-genes encode proteins that exhibit significant similarity to neprilysins in their primary structure, but lack one or more of the motifs required for catalysis.
Summary: Retain the NOT peptidase assertion. The exact protein replaces the first zinc ligand and catalytic glutamate in the neprilysin HExxH motif, while retaining downstream M13 structure. Two alignment strategies and an active mouse control support this loss, consistent with the published Nepl classification.
Reason: Retain the NOT peptidase assertion. The exact protein replaces the first zinc ligand and catalytic glutamate in the neprilysin HExxH motif, while retaining downstream M13 structure. Two alignment strategies and an active mouse control support this loss, consistent with the published Nepl classification.
The reference HEITH motif at 584–588 maps to QQLAH at Nepl19 511–515. Nepl19 retains the M13 fold and downstream ENIAD region but replaces the first zinc-binding histidine and catalytic glutamate with glutamines.
The 21 Nepl-genes encode proteins that exhibit significant similarity to neprilysins in their primary structure, but lack one or more of the motifs required for catalysis.
IKRNOT PMID:34189422 Identification and bioinformatic analysis of neprilysin and ...
ACCEPT
Summary: Retain the NOT peptidase assertion. The exact protein replaces the first zinc ligand and catalytic glutamate in the neprilysin HExxH motif, while retaining downstream M13 structure. Two alignment strategies and an active mouse control support this loss, consistent with the published Nepl classification.
Reason: Retain the NOT peptidase assertion. The exact protein replaces the first zinc ligand and catalytic glutamate in the neprilysin HExxH motif, while retaining downstream M13 structure. Two alignment strategies and an active mouse control support this loss, consistent with the published Nepl classification.
The reference HEITH motif at 584–588 maps to QQLAH at Nepl19 511–515. Nepl19 retains the M13 fold and downstream ENIAD region but replaces the first zinc-binding histidine and catalytic glutamate with glutamines.
The 21 Nepl-genes encode proteins that exhibit significant similarity to neprilysins in their primary structure, but lack one or more of the motifs required for catalysis.
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Review rationale: Conventional metalloendopeptidase activity is refuted by specific disruption of the M13 catalytic apparatus. Exact-sequence alignments map human H584/E585 to Nepl19 Q511/Q512, replacing a zinc ligand and catalytic glutamate; the downstream zinc-binding/catalytic region remains aligned. Two MAFFT strategies agree, and the active mouse control preserves all five sites. The published Nepl classification and existing NOT peptidase annotations agree with this independently reproduced sequence finding. This is pseudoenzyme overannotation, without a claim that the protein lacks a noncatalytic role.
Supporting Evidence:
file:DROME/Nepl19/Nepl19-bioinformatics/RESULTS.md: "The reference HEITH motif at 584–588 maps to QQLAH at Nepl19 511–515. Nepl19 retains the M13 fold and downstream ENIAD region but replaces the first zinc-binding histidine and catalytic glutamate with glutamines."
PMID:34189422: "The 21 Nepl-genes encode proteins that exhibit significant similarity to neprilysins in their primary structure, but lack one or more of the motifs required for catalysis."