Urokinase binds to a plasminogen activator inhibitor type-2-like molecule in placental microvillous membranes.
Biochim Biophys Acta
; 986(1): 135-40, 1989 Nov 17.
Article
em En
| MEDLINE
| ID: mdl-2819091
ABSTRACT
Placental microvillous membranes exhibited saturable binding of urokinase-type plasminogen activator with plateau achieved by 30 min at 4 degrees C and 10 min at 37 degrees C. The binding was essentially irreversible. The capacity was about 8 pmol urokinase per mg membrane protein. Half-maximal displacement of 125I-labelled urokinase was achieved with about 1.0 nM unlabelled urokinase when using 75 micrograms membrane protein/ml. 125I-labelled urokinase did not bind when treated with diisopropylfluorophosphate to block the catalytic activity. Single-chain urokinase (prourokinase), devoid of catalytic activity, did not bind. Catalytically active tissue-type plasminogen activator did compete with 125I-labelled urokinase for binding although less efficiently than urokinase. Binding activity remained in the 100,000 x g pellet after treatment of the membranes with 3 M KCl, alkaline stripping at pH 12 or extraction by the detergent Triton X-100. The binding was essentially blocked by antibodies against plasminogen activator inhibitor-type-2 (PAI-2). Sodium dodecyl sulfate polyacrylamide gel electrophoresis of solubilized membranes with bound 125I-labelled urokinase showed that the urokinase-PAI-2 complexes largely migrated in fractions corresponding to a very large Mr although no clearly defined peaks were observed. It is suggested that PAI-2 occurs in a form anchored to syncytiotrophoblast microvilli, possibly to the cytoskeleton.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Placenta
/
Ativador de Plasminogênio Tipo Uroquinase
/
Inativadores de Plasminogênio
/
Microvilosidades
Limite:
Female
/
Humans
/
Pregnancy
Idioma:
En
Ano de publicação:
1989
Tipo de documento:
Article