The protein tyrosine kinases (PTKs) are involved in many metabolic processes in various signal transduction pathways. P60c-Src is the most abundant non receptor PTK in the platelets (0,2-0,4% of total proteins) and it interacts with contractile proteins (including actin) via its SH-3 domain. It is unclear how p60c-Src is involved in the microfilaments reorganization occurring in platelets aggregation. In this work we show that i) after platelets activation, some changes occur in the interactions between p60c-Src and the contractile systems; ii) these changes are accompanied by changes in the activity of protein tyrosine kinases and phosphatases; iii) part of this changes take place in the membrane. Platelets were stimulated with thrombin (stimulus for 10’’, 30’’, 1’ and 5’) and then fractioned in the three sub-cellular components: cytoskeleton (CSK), cytosol (CS) and membrane-associated skeleton (MSK). P60c-Src and actin in thrombin-stimulated platelets showed a marked migration from MSK to CSK with a transient permanency in the cytosolic fraction. After stimulation the MSK-located p60c-Src becomes dephosphorilated and then results to be rephosphorilated during or after CSK relocation. The p60c-Src kinase activity is not detectable in resting platelets CSK whereas is marked in stimulated platelets CSK. In the cytosolic fraction p60c-Src activity demonstrates opposite behaviour. On the basis of these data we propose that the thrombin-induced microfilaments reorganization leading to aggregate formation requires a specific interaction between actin and phosphorylated p60c-Src in the cytosolic fraction.
INTERACTION OF p60c-Src WITH CONTRACTILE SYSTEMS IN HUMAN PLATELETS
FERRI, Albertino;CALZA, Roberta
1999
Abstract
The protein tyrosine kinases (PTKs) are involved in many metabolic processes in various signal transduction pathways. P60c-Src is the most abundant non receptor PTK in the platelets (0,2-0,4% of total proteins) and it interacts with contractile proteins (including actin) via its SH-3 domain. It is unclear how p60c-Src is involved in the microfilaments reorganization occurring in platelets aggregation. In this work we show that i) after platelets activation, some changes occur in the interactions between p60c-Src and the contractile systems; ii) these changes are accompanied by changes in the activity of protein tyrosine kinases and phosphatases; iii) part of this changes take place in the membrane. Platelets were stimulated with thrombin (stimulus for 10’’, 30’’, 1’ and 5’) and then fractioned in the three sub-cellular components: cytoskeleton (CSK), cytosol (CS) and membrane-associated skeleton (MSK). P60c-Src and actin in thrombin-stimulated platelets showed a marked migration from MSK to CSK with a transient permanency in the cytosolic fraction. After stimulation the MSK-located p60c-Src becomes dephosphorilated and then results to be rephosphorilated during or after CSK relocation. The p60c-Src kinase activity is not detectable in resting platelets CSK whereas is marked in stimulated platelets CSK. In the cytosolic fraction p60c-Src activity demonstrates opposite behaviour. On the basis of these data we propose that the thrombin-induced microfilaments reorganization leading to aggregate formation requires a specific interaction between actin and phosphorylated p60c-Src in the cytosolic fraction.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
