(A) Schematic drawing of the TβRII protein (EC, extracellular domain; TM, transmembrane domain; Kinase, Ser/Thr kinase domain) with the two alternatively spliced exons 2B and 4B. (B) Nucleotide sequence of the cDNA and deduced amino acid sequence of exon 2B (underlined capital letters) and splice site junctions (lower case letters) of the variant TβRIIB are shown. (C) Additionally, the partial nucleotide and amino acid sequence of TβRII without exon 2B is shown. Underlined amino acids indicate amino acid exchange at the splice site junction due to the alternative splicing. Bold letters mark the amino acid and nucleotide exchanges with respect to the human sequence. Arrows indicate the exon boundaries. (hs, homo sapiens; pt, pan troglodytes; mmu, macaca mulatta; mm, mus musculus).