Cell Biology: Plasma membrane2

plasma membrane: 

plasma membrane Assist. Prof. Dr. Wady Chanasut

SPECIALIZED MEMBRANE REGIONS: 

SPECIALIZED MEMBRANE REGIONS Cell junctions occur at points of cell-cell and cell-matrix contact in all tissues Mostly found in epithelial cells interacting plasma membranes are highly specialized in these regions ภาพจาก : Campbell et al., 2006

CELL JUNCTIONS: 

CELL JUNCTIONS Classified to 3 groups according to their function Occluding junctions form a selective permeability barrier across epithelial cell sheets Anchoring junctions connect the cytoskeleton of a cell either to the cytoskeleton of its neighbors or to the extracellular matrix Communicating junctions connect bundles of actin filaments from cell to cell

Occluding junctions: 

Occluding junctions Epithelium cells are selective permeability membrane Separate different chemical fluid from either side of cells The adjacent cell must be sealed together prevents even small molecules from leaking Tight junction – vertebrate only Separate junction – invertebrate mainly ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f2 . gif

TIGHT JUNCTION: 

TIGHT JUNCTION ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f3 . gif

TIGHT JUNCTIONS: 

TIGHT JUNCTIONS ภาพจาก : http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f5 . gif Claudin and Occludin

SEPARATING JUNCTION: 

SEPARATING JUNCTION Mainly found in invertebrate plasma membrane Main occluding junction Unique set of parallel row protein, called Disc-large ภาพจาก : http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f6 . gif

ANCHORING JUNCTIONS: 

ANCHORING JUNCTIONS mechanically attach cells to their neighbors linking transmembrane proteins on adjacent cells Attach to the extracellular matrix Intracellular anchor proteins Transmembrane adhesion protein Two types of anchoring cell junctions: Adherens junction and desmosome Focal adhesions and hemidesmosome ภาพจาก :http :// www . cytochemistry . net / cell - biology / filam . 7 . gif

ANCHORING JUNCTIONS: 

ANCHORING JUNCTIONS

ANCHORING JUNCTION PROTEINS: 

ANCHORING JUNCTION PROTEINS Anchoring junction are composed of two main class proteins Intracellular anchor protein Bind to actin filament Bind to transmembrane adhesion protein Transmembrane adhesion protein Bind to intracellular anchor protein Bind to EMC

ADHERENS JUNCTIONS: 

ADHERENS JUNCTIONS Adherens junctions and desmosomes formed by transmembrane adhesion proteins - cadherin protein family Continuous band or belt that completely encircles the cell Actin bundle are linked via cadherins and anchor protein ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f9 . jpg

DESMOSOME: 

DESMOSOME ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f11 . jpg

FOCAL ADHESION: 

FOCAL ADHESION Focal adhesions and hemidesmosomes bind cytoskeleton to the extracellular matrix transmembrane adhesion proteins - integrin protein family either actin filament or intermediate filament

HEMIDESMOSOME: 

HEMIDESMOSOME Half-desmosome structure connect the basal surface of an epithelial cell to the underlying basal lamina One side of integrins bind to a laminin protein in the basal lamina Another side (intracellular) bind to keratin intermediate filaments.

ANCHORING JUNCTIONS: 

ANCHORING JUNCTIONS Integrins protein family anchor a cell to extracellular matrix molecules cadherin protein family anchor the plasma membrane of both adjacent cells binding to cytoskeletal filaments actin filaments intermediate filaments

COMMUNICATING JUNCTIONS : 

COMMUNICATING JUNCTIONS most cells in animal tissues are in communication via gap junctions the membranes of two adjacent cells are separated by a uniform narrow gap of about 2–4 nm The gap is spanned by channel-forming proteins inorganic ions and other small water-soluble molecules pass directly from the cytoplasm of one cell to the cytoplasm of the other The size of molecules must be <1000 dalton

GAP JUNCTIONS: 

GAP JUNCTIONS ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f15 . jpg

GAP JUNCTION: 

GAP JUNCTION http :// www . mc . vanderbilt . edu / histology / word / 2004 / Cell%20Junctions%2004_files / image013 . jpg http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f16 . jpg

GAP JUNCTION FUNCTION: 

GAP JUNCTION FUNCTION Communications Electrically excitable cells – nerve cells, heart muscle and smooth muscle cells Sharing small molecules metabolites, ions Enbryogenesis – communication between oocyte and granulosa cells Regulation of gap junction pH – ion regulations: Ca2 + , Na + Extracellular signals: neurotransmitters (dopamine)

CONCLUSION ABOUT JUNCTION: 

CONCLUSION ABOUT JUNCTION http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f19 . jpg

PLASMODESMATA: 

PLASMODESMATA ภาพจาก :http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f20 . jpg

PLASMODESMATA: 

PLASMODESMATA ภาพจาก : http :// www . ncbi . nlm . nih . gov / bookshelf / picrender . fcgi?book = mboc4&part = A3469&blobname = ch19f21 . jpg

PLASMODESMATA FUNCTIONS: 

PLASMODESMATA FUNCTIONS Similar to gap junction Allow molecule smaller than 800 Daltons to pass between cell It can be regulated but... Mechanisms still unknown