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#calcium ions

5 public questions tagged with this topic.

Plant tissue culture 2

Which of the following is NOT a fusogen?

Colchicine is not considered fusogen, unlike true fusogenic agents that promote membrane merging of protoplasts. Legitimate fusogens include polyethylene glycol PEG high molecular weight polymer that dehydrates membrane interface creating calcium bridges neutralizing negative charge inducing lipid mixing upon dilution, high concentration calcium ions at alkaline pH around 10.5 similar mechanism reducing electrostatic repulsion, and inactivated Sendai virus bearing fusogenic HN and F glycoproteins that merge animal and plant membranes albeit rarely used now due to biohazard handling. Electrical

Ref: Anne & Harada 1991 fusogens list; Kao 1977 colchicine not fusogen.

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Cell Organelles

The ER lumen contains:

Endoplasmic reticulum lumen is specialized folding compartment with oxidizing redox potential, high calcium millimolar and abundant chaperones distinguishing it from reducing cytosol. Newly translocated polypeptides entering via Sec61 encounter BiP also called GRP78, luminal Hsp70 family member binding transiently to exposed hydrophobic segments in ATP-regulated cycle where ATP binding opens substrate binding domain, hydrolysis closes it trapping unfolded chain preventing aggregation and promoting correct disassembly of aggregates. Cooperation with co-chaperone ERdj proteins stimulates ATPase,

Ref: Kozlov Trends Biochem; ER lumen BiP GRP78 Hsp70 folding quality control UPR sensor.

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