1. Chapter 11 Cell Communication Dr. Joseph Silver

2. this chapter deals with - how cells receive messages - what changes take place in the cell - and what changes take place in the nucleus

3. The goal is to understand 3 processes 1. reception (you pick up a message) 2. transduction (cell response to message) 3. response (what work the message tells the cell to do)

4. how one cell signals another cell is defined by the distance from the signal source to the receptor 5 types are described

5. -direct contact (fig. 11.4) -paracrine (fig. 11.5a) -endocrine (fig. 11.5c) -synaptic (fig. 11.5b) -autocrine (stimulates same cell)

9. the key to everything that goes on in a cell is phosphorylation or dephosphorylation see fig. 11.8, 11.10, and 11.12

11. start or stop inhibit or activate turn on or turn off all happens by adding or removing a phosphate functional group (see page 219)

12. receptors are defined by their location - on a membrane - in a membrane - trans membrane (through) - cytoplasmic

13. there are three types of membrane receptors - channel receptors -enzyme receptors -G protein-coupled receptors

15. some receptors such as steroid hormone receptors are not in the membrane because the message can pass right through the membrane so activation (transduction) takes place in the cytoplasm

18. there are three very important kinases in cells RTK, RSK, RTyK (receptor threonine kinase – serine kinase – tyrosine kinase) these kinases add or remove phosphate from molecules and influence most reactions taking place in every cell

20. see fig 11.15 to see - message to receptor linkage - autophosphorylation - activation of protein by phosphorylation then

21. Go to fig 11.16 to see - activation of 2 nd and 3 rd messengers - activation of enzyme - result of work stimulated by enzyme activity

25. look at fig 11.16 to see amplification of events another word for multiplication in some cases instead of a 1 to 1 relationship there is a 1 to 2, then 2 to 4, then greater amplification as more and more reactions or systems are amplified or inhibited

27. We have previously studied homeodomain proteins (found in all organisms) membrane lipid domains (found in all cell membranes) and multienzyme complexes (increases efficiency) now they are giving in fig 11.18 another name for a multienzyme complex scaffold proteins which holds in place a number of kinase close to each other for increased efficiency

29. Now look at fig 11.9 & 11.10 to see the process from ligand binding to receptor to response by cell

32. there are many kinds of 2 nd and 3 rd etc. messengers

33. Cyclic AMP inositol phosphates calcium and more

37. apoptosis programmed cell death damaged, infected, wrong code,

38. signal for apoptosis can come from inside or outside the cell Ced genes (cell death genes) present as inactive but when activated produce a cascade of proteases known as caspases and nucleases which force cell death