| Registro completo |
| Provedor de dados: |
BJMBR
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| País: |
Brazil
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| Título: |
Dipeptidyl peptidase IV (CD26) activity in the hematopoietic system: differences between the membrane-anchored and the released enzyme activity
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| Autores: |
Pereira,D.A.
Gomes,L.
El-Cheikh,M.C.
Borojevic,R.
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| Data: |
2003-05-01
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| Ano: |
2003
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| Palavras-chave: |
Hematopoiesis
Stroma
Exopeptidase
Ectoenzyme
Membrane rafts
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| Resumo: |
Dipeptidyl peptidase IV (DPP-IV; CD26) (EC 3.4.14.5) is a membrane-anchored ectoenzyme with N-terminal exopeptidase activity that preferentially cleaves X-Pro-dipeptides. It can also be spontaneously released to act in the extracellular environment or associated with the extracellular matrix. Many hematopoietic cytokines and chemokines contain DPP-IV-susceptible N-terminal sequences. We monitored DPP-IV expression and activity in murine bone marrow and liver stroma cells which sustain hematopoiesis, myeloid precursors, skin fibroblasts, and myoblasts. RT-PCR analysis showed that all these cells produced mRNA for DPP-IV. Partially purified protein reacted with a commercial antibody to CD26. The K M values for Gly-Pro-p-nitroanilide ranged from 0.43 to 0.98 mM for the membrane-associated enzyme of connective tissue stromas, and from 6.76 to 8.86 mM for the enzyme released from the membrane, corresponding to a ten-fold difference, but only a two-fold difference in K M was found in myoblasts. K M of the released soluble enzyme decreased in the presence of glycosaminoglycans, nonsulfated polysaccharide polymers (0.8-10 µg/ml) or simple sugars (320-350 µg/ml). Purified membrane lipid rafts contained nearly 3/4 of the total cell enzyme activity, whose K M was three-fold decreased as compared to the total cell membrane pool, indicating that, in the hematopoietic environment, DPP-IV activity is essentially located in the lipid rafts. This is compatible with membrane-associated events and direct cell-cell interactions, whilst the long-range activity depending upon soluble enzyme is less probable in view of the low affinity of this form.
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| Tipo: |
Info:eu-repo/semantics/article
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| Idioma: |
Inglês
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| Identificador: |
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000500003
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| Editor: |
Associação Brasileira de Divulgação Científica
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| Relação: |
10.1590/S0100-879X2003000500003
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| Formato: |
text/html
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| Fonte: |
Brazilian Journal of Medical and Biological Research v.36 n.5 2003
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| Direitos: |
info:eu-repo/semantics/openAccess
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