CMMB 403 Midterm 1 Question and answers 100% correct

CMMB 403 Midterm 1 Question and answers 100% correct CMMB 403 Midterm 1 Describe the RTK signal transduction pathway when activated by the FGF ligand FGF ligand dimerizes RTK receptor. Receptor is phorphorylated and attracts adaptor/GEF. GEF begins phosphorylation cascade: GEF to Ras to Raf to Mek to Erk to TF. TF transcribes gene Describe the JAK-STAT pathway when activated by FGF FGF ligand dimerizes RTK. JAK2 proteins cross-phosphorylate. Both JAK2s phosphorylate a STAT5 (which is a cytoplasmic tyrosine kinase). The STAT5s dimerize and translocate to the nucleus to activates transcription Describe the FgfR3 gene mutation The FgfR3 gene codes for Fibroblast growth factor receptor and is expressed in chondrocytes When the FgfR3 gene is mutated, the JAK-STAT pathway is constantly active, causing cartilage growth to stop before birth. One allelic mutation results in achondroplasia (dwarfism) and homozygous alle mutation results in thanatophoric dysplasia Describe the Hedgehog signal transduction pathway -without ligand -with ligand Without Hh ligand, patched receptor grips smoothened and blocks it from attracting PKA and Slimb. With PKA and slimb still present in the cytoplasm, they work to cleave the Ci (GLI) transcription factor; the cleaved form acts as a repressor With Hh present, it binds to the patched receptor. The patched receptor loosens its grip on smoothened. Smoothened can now bind PKA and slimb, preventing them from cleaving Ci (GLI). Ci (GLI) translocates to nucleus for transcription