Membrane vesicle preparations are very appropriate material for studying the topology of glycoproteins integrated into specialized plasma membrane domains of polarized cells. Here we show that the flow cytometric measurement of fluorescence energy transfer used previously to study the relationship between surface components of isolated cells can be applied to membrane vesicles. The fluorescein ...

Most of the MHC class I peptides presented to the immune system are generated during the course of protein breakdown by the proteasome. However, the precise role of the proteasome, e.g., whether this particle or some other protease generates the carboxyl (C) and amino (N) termini of the presented 8- to 10-residue peptides, is not clear. Here, we show that presentation on Db of ASNENMETM, a pept...

The catalytic concentration of N-acetylalanine aminopeptidase was determined in erythrocytes, polymorphonuclear leukocytes, lymphocytes, alveolar macrophages, human lung fibroblasts, human lung cancer cells, human umbilical vein endothelial cells, mice Leydig cells, rat tumour cells, and endothelial cells from hog and bovine lung. The catalytic concentration ranged from 0.5 +/- 0.1 nU/cell (ery...

A series of novel pyrrolidine derivatives were designed, synthesized and assayed for their inhibitory activities on matrix metalloproteinase 2 (MMP-2) and aminopeptidase N (AP-N). The results showed that these pyrrolidine derivatives exhibited highly selective inhibition against MMP-2 as compared with AP-N. The hydroxamates 8a-c were equally or more potent MMP-2 inhibitors than the positive con...

Aminopeptidase N (APN)/CD13 is a transmembrane ectopeptidase expressed on a wide variety of cells. However, the precise function of APN/CD13 in tumor cells and the relationship of APN/CD13 to thyroid cancer remain unclear. In our study, we quantified the expression of APN/CD13 and additionally dipeptidyl peptidase IV (DPIV)/CD26 in thyroid carcinoma cell lines and in tissues of patients with th...

Aminopeptidase N (APN) is a naturally occurring ectopeptidase present in mammalian semen. Previous studies have demonstrated that APN adversely affects male fertility through the alteration of sperm motility. This enzyme constitutes 0.5 to 1% of the seminal plasma proteins, which can be transferred from the prostasomes to sperms by a fusion process. In the present study, we investigated the mol...

To clone and express the gene encoding chicken aminopeptidase N (chAPN), and analysis the biological function of chAPN expressed in Escherichia coli (E. coli). The chAPN gene was amplified by RT-PCR from the kidney cells of chicken embryo and then cloned into the prokaryotic expression vector pCOLD-TF. Recombinant expression plasmid of pCOLD-TF-chAPN was constructed and then transformed into th...