Cell Signaling Lecture

Cell Signaling Lecture

1. Types of Signaling Molecules

   • Molecules that cross the plasma membrane
     • Gases (NO & CO)
       • Figure 15.5 Figure 13.15
     • Molecules that bind to cell surface receptors
       • Neurotransmitters
         • Figure 15.6
       • Peptide growth factors and hormones
         • Table 15.1 
         • Epidermal growth factor (EGF)
           • Key roles in regulating animal cell proliferation during embryonic development and in adult organisms Figure 15.7
     • Nuclear receptors
       • Transcription facotrs (compose nuclear receptor superfamily) Figure 15.3
       • Steroid Hormones
         • Glucocortioid and Glucocorticoid receptor
           • Ligand-binding induces a conformations change: (1) dissociates the receptor from        Hsp90 (2) enables receptor dimerization Receptor dimers imported into nucleus --> bind DNA regulatory sequences and activate transription of target genes
         • Thyroid hormone receptor
           • Binds DNA regulatory swquences w/in target genes independent of ligand binding In absence of hormones/ligand, receptor interacts w/ corepressors (transcription is repressed) Hormone/ligand binding induces a conformational change in the receptor --> release of corepressors and interaction w/coactivators (transcription is activated)
       • Domains
         • DNA binding
         • Transcriptional activation
       • Steroid hormones, thryroid hormones, vitamin D3, + retinoid acid all BIND + REGULATE "nuclear receptors"

2. Types of Cell Surface Receptors and Mechanisms of Action

   • G protein-coupled receptors
     • Receptor protein-tyrosine kinase
       • Ligand-gated ion channels
         • Cytokine receptors linked to tyrosine kinases
           • Receptor linked to other activities