Research ArticleImmunology

A large Rab GTPase encoded by CRACR2A is a component of subsynaptic vesicles that transmit T cell activation signals

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Science Signaling  22 Mar 2016:
Vol. 9, Issue 420, pp. ra31
DOI: 10.1126/scisignal.aac9171

Recruiting vesicles to activate T cells

T cell activation by antigens involves the formation of a complex, highly dynamic, yet organized signaling complex at the site of the T cell receptors (TCRs). Srikanth et al. found that the lymphocyte-specific large guanosine triphosphatase of the Rab family CRACR2A-a associated with vesicles near the Golgi in unstimulated mouse and human CD4+ T cells. Upon TCR activation, these vesicles moved to the immunological synapse (the contact region between a T cell and an antigen-presenting cell). The guanine nucleotide exchange factor Vav1 at the TCR complex recruited CRACR2A-a to the complex. Without CRACR2A-a, T cell activation was compromised because of defective calcium and kinase signaling.