Latrunculin, 

a toxin secreted by sponges, binds and sequesters G-actin

TLS Online TPP Program

#Id: 7929

#XL - Q Biochemistry

The ER captures selected proteins from the cytosol as they are being synthesized. These are of two types:

Transmembrane proteins

Water-soluble proteins

TLS Online TPP Program

#Id: 7928

#XL - Q Biochemistry

Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

TLS Online TPP Program

#Id: 7927

#XL - Q Biochemistry

Function of the ER:

most eukaryotic cells is to sequester Ca2+ from the cytosol (High concentration of Ca2+-binding proteins in the ER facilitates Ca2+ storage)

TLS Online TPP Program

#Id: 7926

#XL - Q Biochemistry

Rough ER, which is associated with ribosomes, functions in the synthesis and processing of secreted and membrane proteins

Smooth ER, which lacks ribosomes, functions in lipid synthesis.

TLS Online TPP Program

#Id: 7925

#XL - Q Biochemistry

Endoplasmic reticulum

Network of interconnected membranous structures within the cytoplasm of eukaryotic cells contiguous with the outer nuclear envelope.

TLS Online TPP Program

#Id: 7924

#XL - Q Biochemistry

Cardiolipin

an unusual “double” phospholipid containing four fatty acid chains

found primarily in the inner mitochondrial membrane

acts to improve the efficiency of oxidative phosphorylation, by restricting proton flow across the membrane