Summary for peptidase M01.028: aminopeptidase O

Summary Alignment Tree Sequences Sequence features Distribution Literature Human EST Mouse EST Substrates Inhibitors


MEROPS Nameaminopeptidase O
Other namesclone MGC:31762, Mername-AA139 putative peptidase
Name and HistoryAminopeptidase O is an intracellular aminopeptidase with a preference for arginyl bonds (Diaz-Perales et al., 2005).
Domain architecture
MEROPS Classification
Classification Clan MA >> Subclan MA(E) >> Family M1 >> Subfamily (none) >> M01.028
Holotypeaminopeptidase O (Homo sapiens), Uniprot accession Q8N6M6 (peptidase unit: 394-652), MERNUM MER0019730
History Identifier created: MEROPS 6.0 (30 August 2002)
Catalytic typeMetallo
NC-IUBMBNot yet included in IUBMB recommendations.
Activity statushuman: putative
mouse: putative
SpecificityAminopeptidase O has a preference for arginyl bonds but can also release asparagine from peptides. It is also able to convert angiotensin III to angiotensin IV (Diaz-Perales et al., 2005).
Inhibitor commentsAminopeptidase O is inhibited by arphamenine A, which also inhibits aminopeptidase B and leukotriene A4 hydrolase (Diaz-Perales et al., 2005).
StructureAminopeptidase has a C-terminal extension containing an ARM-repeat domain (Diaz-Perales et al., 2005). This is a domain also found in aminopeptidase B and leukotriene A4 hydrolase, and is named after the Drosophila Armadillo protein, which is important for segment polarity. Between the peptidase and ARM-domain there is an 11-mer, basic residue-rich nucleolus location motif (Axton et al., 2008).
LocationAminopeptidase O has been localized to the nucleolus (Axton et al., 2008).
Biological aspectsIn human, aminopeptidase O is mainly expressed in the pancreas, placenta, liver, testis and heart (Diaz-Perales et al., 2005). A shorter isoform has been localized to endothelial and smooth muscle cells in both adult and embryonic blood vessels (Axton et al., 2008). The AOPEP gene also includes a cluster of microRNAs, one of which, miR-27b, has been shown to modulate expression of the Mef2c gene which encodes myocyte-specific enhancer factor 2C (Chinchilla et al., 2011). A microRNA is controlled by the same promoter as its host gene, which is also usually the source of the mRNA inhibited by complementation with the microRNA.
RNA splicingIn the mouse, a shorter isoform is generated from an alternative initiating methionine located near the start of the peptidase domain (Axton et al., 2008).
Other databases TREEFAM
Human genetics
Gene symbol Locus Megabases Ensembl Entrez gene Gene Cards OMIM
C9orf3 9q22.32 ENSG00000148120 84909
Mouse genetics
Gene symbol Position Megabases Ensembl Entrez gene MGI
2010111I01Rik 13:B3 ENSMUSG00000021458 72061 MGI:1919311