Figure 2.

Schematic illustration of the characteristics of TβRI and TβRII. Structural motifs, as well as posttranslationally modified residues and proteolytic cleavage sites are indicated. Green chains of circles, N-linked glycosylations; black circles with white P, phosphorylation sites (auto, receptor autophosphorylation; other kinases indicated: + or − symbols indicate positive or negative impact on receptor kinase activity); gray circles with green Ub, ubiquitin chains (the exact locations of the acceptor lysines are not known); gray circles with purple Su, sumoylation sites; gray circles with blue Ne, neddylation sites. Ubiquitin and NEDD8 are shown as polymeric chains, whereas sumo is illustrated by a monomer, in accordance with the knowledge about these modifications. TβRI is also autophosphorylated on serine/threonine and tyrosine residues, but their exact locations are not known (not shown). Binding of the adaptor protein Shc to a specific phosphotyrosine is also indicated. N-ter, Amino terminal; C-ter, carboxy terminal.