Biomaterial Database

A novel form of dipeptidylpeptidase IV found in human serum. Isolation, characterization, and comparison with T lymphocyte membrane dipeptidylpeptidase IV (CD26). 1995

J S Duke-Cohan, and C Morimoto, and J A Rocker, and S F Schlossman

Division of Tumor Immunology, Dana Farber Cancer Institute, Boston, Massachusetts, USA.

Human CD26, a Type II membrane glycoprotein with intrinsic dipeptidylpeptidase IV (DPPIV) activity and ability to bind adenosine deaminase type I (ADA-1), is expressed on epithelial cells constitutively, but on T lymphocytes its expression is regulated. A soluble form of CD26/DPPIV has been described in plasma and related to immunological status, but it has been defined by the presence of DPPIV activity rather than by isolation. Using nondenaturing chromatographic techniques followed by nondenaturing native preparative electrophoresis, we obtained a homogeneous preparation of soluble serum DPPIV and compared it with a recombinant soluble CD26/DPPIV (rsCD26). We show that serum DPPIV is a monomer of 175 kDa in contrast to rsCD26 of 105-110 kDa, that it exists as a trimer, and that it is probably a serine proteinase. Deglycosylation removed N-linked sugar from both serum DPPIV and rsCD26; no O-linked glycosylation was observed, revealing a protein core of 130 kDa for serum DPPIV. The large serum form expresses functional DPPIV activity with substrate and inhibitor specificities and pH activity profile similar to those of rsCD26. Epitope analysis showed that monoclonal antibodies against five epitopes expressed by rsCD26 also bound, but more weakly, with serum DPPIV. Analysis of peptides after limiting proteolysis and N-terminal sequences reveals no homology with rsCD26 but some identity with other peptidases. Unlike rsCD26, the serum form does not bind ADA-1 and has no ADA-1 already associated with it. Similarly to rsCD26, serum DPPIV is a potent T cell costimulator. We conclude that the serum form of DPPIV is unique and is not a breakdown product of membrane CD26. The conservation of DPPIV activity and five epitopes specific to rsCD26 suggest, however, a significant structural similarity.

UI	MeSH Term	Description	Entries
D008213	Lymphocyte Activation	Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.	Blast Transformation,Blastogenesis,Lymphoblast Transformation,Lymphocyte Stimulation,Lymphocyte Transformation,Transformation, Blast,Transformation, Lymphoblast,Transformation, Lymphocyte,Activation, Lymphocyte,Stimulation, Lymphocyte
D008297	Male		Males
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000243	Adenosine Deaminase	An enzyme that catalyzes the hydrolysis of ADENOSINE to INOSINE with the elimination of AMMONIA.	Adenosine Aminohydrolase,Aminohydrolase, Adenosine,Deaminase, Adenosine
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000939	Epitopes	Sites on an antigen that interact with specific antibodies.	Antigenic Determinant,Antigenic Determinants,Antigenic Specificity,Epitope,Determinant, Antigenic,Determinants, Antigenic,Specificity, Antigenic
D013601	T-Lymphocytes	Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.	T Cell,T Lymphocyte,T-Cells,Thymus-Dependent Lymphocytes,Cell, T,Cells, T,Lymphocyte, T,Lymphocyte, Thymus-Dependent,Lymphocytes, T,Lymphocytes, Thymus-Dependent,T Cells,T Lymphocytes,T-Cell,T-Lymphocyte,Thymus Dependent Lymphocytes,Thymus-Dependent Lymphocyte
D018819	Dipeptidyl Peptidase 4	A serine protease that catalyses the release of an N-terminal dipeptide. Several biologically-active peptides have been identified as dipeptidyl peptidase 4 substrates including INCRETINS; NEUROPEPTIDES; and CHEMOKINES. The protein is also found bound to ADENOSINE DEAMINASE on the T-CELL surface and is believed to play a role in T-cell activation.	Antigens, CD26,CD26 Antigens,Dipeptidyl-Peptidase IV,Adenosine Deaminase Complexing Protein 2,CD26 Antigen,Antigen, CD26,Dipeptidyl Peptidase IV