Lipid is hydrophobic while cytosol is hydrophilic, therefore we need a monolayer of phospholipids so that the hydrophilic heads interact with the cytosol and the hydrophobic tails interact with the triacylglycerols.
On the surface of the droplet, we have a network of perillipin, these proteins are useful for recruiting lipases.
As explained above, phospholipids are excellent for storing triacylglycerol because their hydrophilic head face the aqeuous environment, while their hydrophobic tail face the densely packed triacylglycerol.
The first and second lipase needs to be recruited to the lipid droplet to be active.
MGL (i.e. the 3rd lipase) is constitutively active in the cytosol.
ATGL (i.e. the 1st lipase) is recruited to the lipid droplet based on a binding partner in the perilipin network.
HSL (i.e. the 2nd lipase) is phosphorylated by PKA to facilitate recruitment to the lipid droplet.
Adrenaline is the right signal, but it does not degrade lipases.
Hormone bind to the plasma membrane G protein coupled beta adrenergic receptor, not on the surface of the lipid droplet.
The surface of lipid droplet is phospholipid, not sphingolipid.
The correct answers are:
Catecholamines triggers a signaling cascade that activates a key kinase (PKA), and
The perilipin network rearrange to promote recruitment of lipases
This is a fill in the blank problem, the blanks are already filled in the question above.
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