Fig. 1.

Schematic diagram of growth hormone (GH) receptor signaling and gene activation. GH (purple triangle) binds to its receptor, causing both receptor dimerization and activation of the associated intracellular tyrosine kinase, Jak2, which phosphorylates itself and the GH receptor on tyrosine residues (each indicated as P within a yellow circle). A series of intracellular signal transduction pathways are activated, which mediate the biological effects of GH. Signal transducer and activator of transcription (Stats) 1, 3, 5a, and 5b are recruited to the GH receptor and become tyrosine phosphorylated, leading to their dimerization and translocation into the nucleus, where they bind to DNA in chromatin of target genes and activate gene transcription (indicated by bent arrows at transcription start sites)