When protein does not fit membrane well = hydrophobic mismatch. 

Such event can occur during the insertion of protein into the membrane, but hydrophobic-hydrophilic forces will try to return it to the right position.

1) the lipid bilayer can adjust to the hydrophobic mismatch : lipid hydrocarbon chains are quite flexible, so the can be stretched, squashed, and/or tilted

2) non-bilayer lipids are often involved in this kind of adjustment : their introduction into membrane can change its thickness.

3) changes in the tilting angle of TM-helices can be employed to adjust proteins 4) because proteins often require certain lipids to function, proteins could migrate in the membrane until they find needed protein. i.e. cardiolipin needs PLP. 

This graph illustrates the activity of a NADH dependence from membrane properties (artificial bilayer). Line b – aceton, line a – natural, line e – artificial, better than natural one. From line to line concentration of phospholipids increases. Why did not nature do membrane that equals e? Probably because: no evolutionary pressure, interactions with other parts of membrane.

A = free, unbound protein (10 -100 nm2/c)

B  = tightly assosiated with cytosceleton

C = move along cytosceleton

D = part of big complex (micro domain), restricted in movements

E = lipid raft 

F = associated with external matrix

Micro domains within cell membranes that are enriched in certain lipids such as cholesterol, glycolipids and sphingolipids 

- they form domains of typical size that seem not to mix or fuse with each other

- their alleged role in cellular signaling, trafficking, and structure has yet to be determined despite many experiments

- their very existence is still controversial debated 

monolayer lipids based on isoprenoids 

Even

C2 enrichment

1) short (<6), 2) medium (6 – 12) for storage 3) long (14 – 20) 4) very long chain (>22)

Fully saturated

Unsaturated: poly and mono

- no carbon-carbon double bonds

- solid at room temperature

- relative stable against rancidification (auto-oxidation)

- meat and meat products, milk and milk products, tropical oils

(coconut oil, palm oil) 

Δ - from carboxy group

ω - from methyl end

 - only one carbon double bond

 - liquid at room temperature

 - relatively stable against rancidification

- found in plant oil and animal fat

 - multiple double carbon bonds

 - liquid even below room temperature

 - unstable, prone to rancidification

 - includes many essential fatty acids