Model for assembly of the cytoplasmic capping complex.

In this model Nck1 serves as the scaffold for assembly of the cytoplasmic capping complex, with the 5′-kinase and CE juxtaposed by binding to adjacent domains. The ubiquitination site between the second and third SH3 and the SH2 domain for binding tyrosine phosphoproteins (pTyr) are indicated by red arrows. It has yet to be determined how the methyltransferase joins the complex to complete the reaction.