Channel transport schematic representations

Figure 1. Schematic representations of significant biological functions displayed by host-guest complexation in homogeneous solutions or at membrane surfaces, (a) Separation (e.g., antibody-antigen complex formation), (b) Transformation (e.g., enzymatic reaction), (c) Translocation (e.g., carrier- or channel-mediated transport), (d) Transduction (e.g., receptor-mediated transmembrane signaling).

Fig. B.6.1. Schematic representation of the action of gramicidin A (a), an ionophore (b), and a ligand-controlled ion channel (c) in the transport of ions across a biological membrane.

Figure 1 A schematic representation of the Ca + transporters of animal cells. Plasma membrane (PM) channels are gated by potential, ligands or by the emptying of Ca + stores. Channels in the ER/SR are opened by lnsP3 or cADPr (the cADPr channel is sensitive to ryanodine and is thus called RyR). ATPase pumps are found in the PM (PMCA), in the ER/SR (SERCA), and in the Golgi apparatus (SPCA). The nuclear envelope, which is an extension of ER, contains the same transporters of the latter. NCXs are located in the PM (NCX) and in the inner mitochondria membrane (mNCX). A uniporter (U) driven by the internal negative potential (-180 mV) transports Ca + into mitochondria. Ca +-binding proteins are represented with a sphere containing the four EF-hands Ca +.binding sites.

Schematic representation of the major pathways for the transport of Ca across cellular membranes. PM, plasma membrane ER(SR), endoplasmic reticulum (sarcoplasmic reticulum) M, mitochondria A P, difference in membrane potential. The transport proteins shown are 1 and 2, PM and ER(SR) Ca -ATPases 3 and 4, PM and ER(SR) receptor-mediated Ca " channels 5 and 6, PM and M (inner-membrane) Na /Ca exchangers 7 and 8, PM and M voltage-sensitive Ca channels. In addition, some not-well-defined passive transport pathways are indicated by dashed arrows.

Figure 3 Schematic representation of proposed functions of the CFTR. The absence of a functional CFTR in cystic fibrosis has been shown to stimulate the activity of epithelial Na channels (ENaC), leading to the conclusion that CFTR serves to inhibit these channels in normal subjects. CFTR has also been shown to transport bicarbonate anion and reduced glutathione across the apical epithehal plasma membrane. Studies have also suggested that CFTR may serve as a receptor for Pseudomonas aeruginosa.

Figure 3 Schematic representation of the channel and carrier mechanism and classification of the different types of transport.

Figure 2. Channel transport representations, (a) Schematic illustration of the channel transpat.

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