Original sentence: Engagement of the TCR with antigen and MHC results in activation of its T lymphocyte through a series of biochemical events mediated by associated enzymes, co-receptors, and specialized accessory molecules
Edited sentence: CD45 - The transmembrane tail of which functions as a Tyrosine phosphatase).Early signally steps implicate the following kinases in TCR associated reactions.Engagement of the TCR with antigen and MHC results in activation of its T lymphocyte through a series of biochemical events mediated by associated enzymes, co-receptors, specialized accessory molecules, and activated or released transcription factors.Fyn - Associated with ITAMs of the IgAlpha and Igbeta regions of the TCR complex.Lck - Associated with the transmembrane tail of CD4.T-cells largely utilise the SRC family of kinases in transmembrane signalling to phosphorylate tyrosines that are part of  immunoreceptor tyrosine/based activation motifs (ITAM).The essential function of the TCR complex is to identify specific bound antigen and elicit a distinct and critical response.The mechanism by which a T-cell illicits this response upon contact with its unique antigen is termed T-cell activation.The most common mechanism for activation and regulation of molecules beneath the lipid bilayer is via phosphorylation/dephosphorylation by protein kinases.There are a myriad of molecules involved in the complex biochemical process by which this occurs which, in a wider context, is generally termed trans-membrane signalling.Zap70 - Binds to ITAM sequences upon phosphorylation by Lck and Fyn