{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 5 Synaptic Transmission

G protein systems relatively small just a receptor

Info icon This preview shows pages 5–6. Sign up to view the full content.

View Full Document Right Arrow Icon
G-Protein Systems ((relatively small. Just a receptor not a lot of biological functions in itself,but link to biochemical pathways.) o G-protein-coupled receptor 1 polypeptide/ 1 subunit 7 membrane spans binds to G protein binds NT 2 functions – has to interact with NT and G protein o G-Protein (much more complex) 3 polypeptides/subunits (can have functionally distinct effects on other parts of the cell) binds to G-protein-coupled receptor binds guanosine triphosphate (GTP) (breaking down GTP causes changes of conformation in protein leading to inactivation or activation of G- protein) have enzymatic activity (can catalyze reactions) G-Proteins & Effector Proteins (have complex effects) o inactived effector – no influence on other proteins o activated effector – influence other proteins o converts neurotransmitter to intracellular chemical information (i.e. activation of effector enzymes/proteins (effector protein)) phosporylation of proteins o phosphorylation controls protein activity o protein ↔ protein – PO 4 ( protein kinase (add phosphate group) ↔ protein phosphotase(remove phosphate group) (inactivate ↔ active) Multiple sites can modulate enzyme activity o covalent modulation – chemical bonds formed e.g. adding phospate o allosteric modulation – changing shape (like chemical-gated channel) o NT receptor interactions are a from of allosteric modulation G-Proteins & Second Messengers o g-protein activates primary effector o primary effector generates a second messenger o second messenger activates second (downstream) Effectors cAMP system o cAMP serves as an intracellular (“second”) message for many effector proteins; “cAMP-dependent protein kinases” eg protein kinase A
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
o G-Proteins can turn system “on” or “off” ie Gs vs Gi o note” same transmitter can act on Gs or Gi therefore effect depends on proteins expressed in post-synaptic cell. Effectors can modulate gene expression o downstream effector are transcription factors produces very long-term effects on neuron Amplification in 2 nd messenger pathways o transmitter activates receptor o receptor activates G-protein o g-protein stimulates adenylyl cyclase to convert ATP to cAMP o cAMP activates protein kinase A o protein kinase A phosporylates potassium channels G-Proteins and the shortcut pathway o Activated G-Protein modulates ion channel o indirect NT gating of ion channel o effects are via phosphorylation of channel; ie long-term gating IP 3 and DAG System o both IP3 and DAG serve as an intracellular messages for many effector proteins (“divergence” in system) o G-proteins can turn system “on” or “off” o all G-proteins are referred to as Go Chapter 5 Notes Electrical Synapses allow ionic current to pass equally well in both directions six connexin subunits comprise one connexon, two connexons comprise one gap juntion channel, and many gap junction channels comprise one gap junction.
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern