The placental leucine aminopeptidase (P-LAP), adipocyte-derived leucine 
aminopeptidase (A-LAP) and leukocyte-derived aminopeptidase (L-RAP) belong to 
one distinct group of the M1 family of amimopeptidases, which we term the 
"Oxytocinase subfamily". They share HEXXH(X)18E Zn-binding and GAMEN motifs 
essential for the enzymatic activities. Intracellular localization is the 
characteristic feature of the subfamily members. While P-LAP is translocated 
from intracellular vesicles to plasma membrane in a stimulus-dependent manner, 
both A-LAP and L-RAP are retained in the endoplasmic reticulum. They contain 
sequences necessary for the specific localization in the cell. It is getting 
evident that the subfamily members play important roles in the maintenance of 
homeostasis including maintenance of normal pregnancy, memory retention, blood 
pressure regulation and antigen presentation. In this review, current situation 
of this newly identified subfamily is summarized.