Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.17.21 (prostate-specific membrane antigen)
 1,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, a novel M(r) 100,000 prostate-specific membrane glycoprotein (PSM) has been detected by the prostate-specific monoclonal antibody 7E11-C5, raised against the human prostatic carcinoma cell line LNCaP. The PSM antigen is expressed exclusively by normal and neoplastic prostate cells and metastases. We now report the molecular cloning of a full-length 2.65-kilobase complementary DNA encoding the PSM antigen from a human LNCaP complementary DNA library by polymerase chain reaction using degenerate oligonucleotide primers. Analysis of the complementary DNA sequence has revealed that a portion of the coding region, from nucleotide 1250 to 1700, has 54% homology to the human transferrin receptor mRNA. The deduced polypeptide has a putative transmembrane domain enabling the delineation of intra- and extracellular portions of this antigen. In contrast to prostate-specific antigen and prostatic acid phosphatase which are secreted proteins, PSM as an integral membrane protein may prove to be effective as a target for imaging and cytotoxic targeting modalities.
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PMID:Molecular cloning of a complementary DNA encoding a prostate-specific membrane antigen. 841 12

Prostate specific membrane antigen (PSMA) is a novel prostate marker that is highly expressed in normal prostate as well as in prostate cancer. Its expression is increased in prostate cancer and is found primarily in the prostate. PSMA is considered to be a type II membrane protein with a 54% homology to the transferrin receptor. However, in normal prostate, PSM', an alternatively spliced form of PSMA, is localized in the cytoplasm. The PSMA functions as both a neurocarboxypeptidase and folate hydrolase and may therefore be involved in the neuroendocrine regulation of prostate growth and differentiation. The implication of these findings is currently under investigation. In this article the cloning of the PSMA gene, its possible role as a therapeutic target and its implication as a diagnostic tool with regard to the molecular staging of prostate cancer is reviewed.
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PMID:[Significance of prostate-specific membrane antigen (PSMA). A neurocarboxypeptidase and membrane folate hydrolase]. 899 30

Membrane glutamate carboxypeptidase (mGCP) hydrolyses pteroylpoly-gamma-glutamates, methotrexate tri-gamma-glutamate and N-acetyl-aspartyl-alpha-glutamate. The enzyme is thought to be required for intestinal uptake of folate, for the resistance of some tumours to methotrexate, and for the metabolism of N-acetyl-aspartyl-glutamate, an abundant neuropeptide. It has recently been reported that mGCP is a protein also known as prostate-specific membrane antigen, homologous with transferrin receptor. This allows us to predict the domain structure of mGCP. Moreover, we have been able to assign the catalytic domain of mGCP to peptidase family M28, which contains cocatalytic zinc metallopeptidases. On the basis of the known structure of an aminopeptidase in family M28, we predict that Asp377, Asp387, Glu425, Asp453 and His553 are ligands of two atoms of zinc bound in the catalytic site of mGCP, and suggest that the aminopeptidases of Vibrio and Streptomyces can serve as valuable models in the design of inhibitors for this medically important enzyme.
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PMID:Structure of membrane glutamate carboxypeptidase. 918 45

The transferrin receptor (TfR) undergoes multiple rounds of clathrin-mediated endocytosis and reemergence at the cell surface, importing iron-loaded transferrin (Tf) and recycling apotransferrin after discharge of iron in the endosome. The crystal structure of the dimeric ectodomain of the human TfR, determined here to 3.2 angstroms resolution, reveals a three-domain subunit. One domain closely resembles carboxy- and aminopeptidases, and features of membrane glutamate carboxypeptidase can be deduced from the TfR structure. A model is proposed for Tf binding to the receptor.
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PMID:Crystal structure of the ectodomain of human transferrin receptor. 1053 Oct 64

The Aeromonas proteolytica aminopeptidase (AMP), Pseudomonas sp. (RS-16) carboxypeptidase G2 (CPG2), and Streptomyces griseus aminopeptidase (SGAP) are zinc dependent proteolytic enzymes with cocatalytic zinc ion centers and a conserved aminopeptidase fold. A BLAST search with the sequence of the solved AMP structure indicated that a similar domain could be found in prostate-specific membrane antigen (PSMA) and the transferrin receptor (TfR). When the PSMA or TfR sequence was input into the THREADER program, the top structural matches were SGAP and AMP confirming that these are structurally conserved domains. Optimal sequence alignment of PSMA and TfR using the known three-dimensional structures of AMP, CPG2, and SGAP shows that the critical amino acids involved in forming the catalytic pocket are conserved in PSMA but absent in the TfR. The specificity pocket in AMP is formed from four aromatic side chains and the equivalent region in CPG2/PSMA has a changed sequence pattern. Since CPG2 and PSMA are folate hydrolases, the changed specificity pocket leaves space to accommodate the large pteroate moiety of folic acid. In contrast, no enzyme function has been ascribed to the TfR.
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PMID:The extracellular regions of PSMA and the transferrin receptor contain an aminopeptidase domain: implications for drug design. 1059 64

For experimental immunotherapy of prostate cancer, we used a model system to target a defined region of the extracellular domain of prostate-specific membrane antigen (PSMA). PSMA is a surface antigen expressed by prostate epithelium that is upregulated approximately 10-fold in most prostate tumors. We vaccinated BALB/c mice with NIH3T3 cells cotransfected with pST/neo plus pEF-BOS-based vectors expressing either the full-length 750-amino acid human PSMA or only the C-terminal 180-amino acid region (PSMc). PSMc lies C-terminal to the transferrin receptor-like sequence in the extracellular domain of PSMA. BALB/c mice were injected i.p. 4 times at weekly intervals with vaccine cells. Vaccinated mice were then challenged s.c. with Renca/PSMA, a BALB/c renal cell carcinoma line transfected to express human PSMA. Growth of Renca/PSMA tumors was substantially retarded and host survival significantly prolonged in mice prevaccinated with either 3T3/PSMA or 3T3/PSMc. Furthermore, antiserum from vaccinated mice intensely immunocytochemically stained LNCaP, a PSMA-positive human prostate cancer cell line. In contrast, control mice similarly prevaccinated i.p. with 3T3/neo (NIH3T3 cells transfected with pST/neo alone) developed Renca/PSMA tumors, which were palpable within 2 weeks and lethal by 5 weeks. Serum from 3T3/neo-vaccinated mice did not immunocytochemically stain LNCaP cells. The antitumor activity induced by vaccination with 3T3/PSMc was also demonstrated via growth inhibition of established LNCaP tumors xenografted in athymic mice following passive transfer of immune serum from vaccinated mice. Our results suggest that vaccination with PSMc induces adaptive humoral activity, which is directed against the extracellular region of human PSMA and can significantly inhibit human prostate cancer growth in athymic mice, and that administration of antibodies to PSMA may provide a passive treatment modality for immunocompromised patients.
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PMID:Inhibition of prostate-specific membrane antigen (PSMA)-positive tumor growth by vaccination with either full-length or the C-terminal end of PSMA. 1239 43

The transferrin receptor family is represented by at least seven different homologous proteins in primates. Transferrin receptor (TfR1) is a type II membrane glycoprotein that, as a cell surface homodimer, binds iron-loaded transferrin as part of the process of iron transfer and uptake. Other family members include transferrin receptor 2 (TfR2), glutamate carboxypeptidase II (GCP2 or PSMA), N-acetylated alpha-linked acidic dipeptidase-like protein (NLDL), N-acetylated alpha-linked acidic dipeptidase 2 (NAALAD2), and prostate-specific membrane antigen-like protein (PMSAL/GCPIII). We compared 86 different sequences from 24 different species, from mammals to fungi. Through this comparison, we have identified several highly conserved residues specific to each family not previously associated with clinical mutations. The evolutionary history of the TfR/GCP2 family shows repeated episodes of duplications consistent with recent theories that nondispensable, slowly evolving genes are more likely to form multiple gene families.
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PMID:Molecular evolution of the transferrin receptor/glutamate carboxypeptidase II family. 1716 Jun 44

Glutamate carboxypeptidase III (GCPIII) is a metalloenzyme that belongs to the transferrin receptor/glutamate carboxypeptidase II (GCPII; EC 3.4.17.21) superfamily. GCPIII has been studied mainly because of its evolutionary relationship to GCPII, an enzyme involved in a variety of neuropathologies and malignancies, such as glutamatergic neurotoxicity and prostate cancer. Given the potential functional and pharmacological overlap between GCPIII and GCPII, studies addressing the structural and physiological properties of GCPIII are crucial for obtaining a deeper understanding of the GCPII/GCPIII system. In the present study, we report high-resolution crystal structures of the human GCPIII ectodomain in a 'pseudo-unliganded' state and in a complex with: (a) L-glutamate (a product of hydrolysis); (b) a phosphapeptide transition state mimetic, namely (2S,3'S)-{[(3'-amino-3'-carboxy-propyl)-hydroxyphosphinoyl]methyl}-pentanedioic acid; and (c) quisqualic acid, a glutamate biostere. Our data reveal the overall fold and quaternary arrangement of the GCPIII molecule, define the architecture of the GCPIII substrate-binding cavity, and offer an experimental evidence for the presence of Zn(2+) ions in the bimetallic active site. Furthermore, the structures allow us to detail interactions between the enzyme and its ligands and to characterize the functional flexibility of GCPIII, which is essential for substrate recognition. A comparison of these GCPIII structures with the equivalent GCPII complexes reveals differences in the organization of specificity pockets, in surface charge distribution, and in the occupancy of the co-catalytic zinc sites. The data presented here provide information that should prove to be essential for the structurally-aided design of GCPIII-specific inhibitors and might comprise guidelines for future comparative GCPII/GCPIII studies.
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PMID:Structural insight into the evolutionary and pharmacologic homology of glutamate carboxypeptidases II and III. 1967 40