Related Experiment Video
Updated: May 23, 2026

An In Vitro Assay to Study Platelet Migration Using RGD-Functionalized Avidin-Biotin Tethers
Published on: November 8, 2024
Peptide LSARLAF induces integrin β3 dependent outside-in signaling in platelets
Haixia Niu1, Zhenlu Xu, Ding Li
1Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Introduction:
Peptide LSARLAF (LSA) can bind and activate integrin αIIbβ3 in the absence of 'inside-out' signal. The active αIIbβ3 mediates 'outside-in' signaling that elicits platelet aggregation, granule secretion and TxA2 production. Here we identify the membrane glycoproteins which mediate LSA-induced platelet activation other than αIIbβ3, and determine the roles of Src, PLCγ2, FcRγ-chain, and SLP-76 in LSA-induced platelet activation.
Method:
Ligand-receptor binding assay was performed to study the effect of peptide LSA or its control peptide FRALASL (FRA) on integrins binding to their ligands. Spreading of CHO cells expressing αIIbβ3 or αVβ3 on immobilized fibrinogen was measured in the presence of LSA or FRA. Washed β3, Src, FcRγ-chain, LAT and SLP-76 deficient platelets aggregation and secretion were tested in response to LSA.
Results:
Ligand-receptor binding assay indicated that LSA promoted the binding of multiple ligands to αIIbβ3 or αVβ3. LSA also enhanced CHO cells with αIIbβ3 or αVβ3 expression spreading on immobilized fibrinogen. β3 deficient platelets failed to aggregate and secrete in response to LSA. The phosphorylation of PLCγ2 and Syk was also β3 dependent. Src, FcRγ-chain, LAT and SLP-76 deficient platelets did not aggregate, secrete ATP or produce TxA2 in response to LSA.
Conclusion:
LSA-induced platelet activation is β3 dependent, and signaling molecules Src, FcRγ-chain, SLP-76 and LAT play crucial roles in LSA-induced β3 mediated signaling.
Related Concept Videos
Intracellular Signaling Affects Focal Adhesions
Some...
Activation of Integrins
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
Selectins
IP3/DAG Signaling Pathway
Laminins are the Adhesive Proteins of Basal Lamina
In humans, the five forms of alpha chains are LAMA 1, LAMA 2, LAMA 3, LAMA 4, and LAMA 5. The four forms of beta chains are LAMB 1, LAMB 2, LAMB 3, and LAMB 4. The three forms of gamma...
Integrins
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...

