How Protein Works - Episode 2: Protein Synthesis


hey guys I'm back with my second episode

in my how protein works series in this

episode we're talking about protein

synthesis now I'm taking you guys back

probably high school biology you

probably learned some of this stuff but

you probably didn't really know what it

meant at the time so in order to

synthesize new muscle proteins we have

to engage the process of what's called

muscle protein synthesis now protein

synthesis is in general is basically

making protein from our DNA code alright

so if we have a protein like most

hormones for you most hormones for

example like insulin are proteins

they're chains of amino acids and the

way they fold gives them their activity

okay we call that the 3d conformational

structure but that information to make

those proteins is encoded in our DNA

all right same thing for our muscle

proteins like actin myosin Titan desman

all those are coated in our DNA so let's

say we do something and it sends a

signal to the cell mic resistance

training that causes us to increase the

rate of synthesizing myosin or other

proteins in skeletal muscle well how

does that actually work well here we

have DNA which is double-stranded okay

so deoxyribonucleic acid

it is double-stranded and it undergoes

the for the signal ascent it undergoes

the process of transcription again these

aren't on-and-off processes like we

talked about last time these are always

going on but it's the relative rates

that make the difference in anabolism so

this process of transcription is

basically translating mister sorry

transcribing this DNA sequence into a

comparable mRNA sequence ok mrna stands

for messenger messenger RNA and each

three nucleotide sequence is going to

code for a specific amino acid and we're

going to talk a little bit more about


but but basically this mRNA the code in

this mRNA is going to depend on the code

in the DNA okay so this is transcribed

that's what we call and you get this

mRNA now with this mRNA in order to get

that information into an actual peptide

or protein to make a protein we have to

have we have to go through a process

called translation okay

and translation is the process of taking

this mRNA and translating it into a

protein and we do that using something

in the cell called a ribosome okay

and this ribosome basically what it does

is it hooks up with the RNA and it goes

along and it literally translates it and

the way it does that is each three

nucleotide sequence in the mRNA

corresponds to a specific amino acid all

right so the ribosomes gonna hook on

here read the first mRNA read the first

three nucleotide sequence grab an amino

acid that matches that sequence and

start the chain and then it's going to

go to the next three nucleotide sequence

and attach another amino acid and then

the next three nucleotide sequence and

attach another meal acid and it's going

to keep doing that until it forms the

fully formed protein okay so again by we

are producing a protein that is coded

for in the DNA through the process of

transcription and translation now in

skeletal muscle the rate limiting step

of muscle protein synthesis is the

translation step and specifically the

the rate limiting step is the ribosome

hooking up to the mRNA the rate limiting

step of that attachment is the formation

of a scaffold complex called AI f4f okay

IIF for F is a complex on the ribosome

that acts as a scaffold for the ribosome

to it

attached to the mRNA okay so what

regulates the formation of that scaffold

are two proteins called

EF for G and E if' for e okay

and those Prost proteins when they when

they increase in their binding that

increases the production of that

scaffold and the ribosome can get on the

mRNA all right so these are regulated by

a protein called mTOR alright in TOR is

called as is denoted for the million

target of rapamycin is why it's called

mtar in TOR is kind of your amino acid

for lack of better terms sensor for the

cell your anabolic sensor okay so it has

inputs from a KT which is sensitive to


okay so insulin is a positive regulator

of mTOR even though insulin really

doesn't increase muscle protein

synthesis in humans the signal gets too

diluted by the time it gets to here

EMP kinase is a negative regulator and P

kinase is the energy sensor of the cell

okay so for example if ATP levels go up

that will block a MP kinase which makes

impor more active okay if ATP levels go

down that means a MP levels go up and

increase the activity of a MP kinase

which blocks in TOR now think about this

for a second if you were in a negative

calorie balance doing a lot of cardio

these sorts of things you didn't have a

lot of energy you would be activating AP

kinase blocking mTOR and that makes

sense from a theological perspective

because if you were low in energy you

would not be want to want to be wasting

a lot of energy making new muscle

proteins or proteins in general okay

it's an energetically expensive process

so that's why one of the reasons that a

calorie deficit typically is not

anabolic sorry a written fasters so in

tour what it's activated and it can be

activated mostly what we're gonna talk

about is the amino acid leucine


mTOR okay leucine seems to have evolved

the body seems to have evolved to

instead of sensing every single amino

acid it senses leucine is kind of its

sensor for protein sufficiency okay so

as cellular levels of leucine increase

that increases the activity dim tour in

tour blocks a probe phosphorylates a

protein jeez mTOR phosphorylates a

protein called ef4 be alright bear with


IIF 4b binds to ëif 4e which reduces its

availability to bind with E is 4g thus

reducing the production of the scaffold

complex a f4f and thus reducing the

ribosomal attachment to the mRNA and

reducing translation and thus muscle

protein synthesis okay so if we want

protein synthesis to proceed this is a

rate limiting step we have to

phosphorylate this e is for B and

phosphorylation merely means we're

adding a phosphate group to it okay mTOR

is what's called a kinase and kinase

phosphorylates so when mTOR is

active it phosphorylates this that

reduced that takes away the inhibition

of AF for be on e if4 e di f 4e is now

free to bind with the if4 G to assemble

this scaffold complex CIF for F and

muscle protein synthesis can proceed

mTOR also specifically activates the

ribosomal protein P 70 s 6k P 70 s 6k

actually increases the production of

specific proteins involved in the

process of muscle protein synthesis so

not only

are you getting increased muscle protein

synthesis you're getting increased

capacity for muscle protein synthesis by

activating this protein all of these

things lead to increased muscle protein

synthesis but it was all triggered by

things that happened at this step right

here in tor right so leucine seems to be

the most potent nutritional regulator of

mTOR all right now some of you may say

why not just take leucine all day well

good question and the answer is very


well I would why why do we have to eat

protein why couldn't we just eat leucine

well that's a great question and it can

be answered very simply if you remember

if we're building if we have this

ribosome terrible handwriting that is

attaching to an mRNA and reading this

translating this mRNA and we're

producing a protein remember that we had

amino acids in the cell that we're

getting attached to this that we're

coming into the ribosome and used to

fillet the growing peptide chain if you

only intake leucine what is going to

likely happen is your levels of other

essential amino acid levels are

eventually going to fall low enough to

the point where it is actually going to

run out of those to build the growing

peptide chains and essentially short

circuit muscle protein synthesis that is

why just giving leucine is not going to

make you more anabolic leucine something

the leucine can be a recovery agent

there are some recovery benefits in

terms of muscle soreness and some other

things we'll get into later but just

leucine by itself is not going to build

muscle will increase muscle protein

synthesis transiently but it will not

build muscle you need the you need

protein with it now some of you may be

saying well that means leucine is a

waste of money keep in mind most people

who were in bodybuilding already

my protein diet so they're not gonna run

out of these amino acids so you don't

worry about that that happening now

whether or not Lucy is a valuable

supplement for people that's still kind

of up for debate

some people tell you it's worthless I

think there may be some benefits in

terms of recovery outside your normal

protein intake but I'm certainly not

gonna argue with anybody who says that

it's not going to help you build muscle

it doesn't seem to be a muscle building

supplement it seems to be a recovery

agent but that's the process so remember

if you're looking at things we're going

from DNA to RNA to protein if we're

going to summarize these things that is

the process of muscle protein synthesis

this is transcription this is

translation okay one more point I want

to make in terms of muscle protein

synthesis is that the capacity and

possibly your genetic limit for how much

muscle you can gain a lot of that may be

determined by something called my own

nuclear domain theory that is how many

satellite cells you have available to

fuse as my own nuclei let me give you an

example and I'll talk about the reasons

why if this is our muscle just bear with

me here it is our muscle muscle as well

as I believe is the only type of cell

muscle cells the only type of cell each

fiber is actually a cell that is

multinucleated that is it has more than

one nucleus all right nucleus remember

is like the brain of the cell right it

controls both so pretty typical so you

actually have multinucleated muscle

cells alright but you also have what's

called satellite cells is

it's it out here and if the right things

happen these guys confuse and become my

own nuclei they can become nucleuses all

right lifting weights increases

satellite cell fusion why is that

helpful well each of these my own nuclei

are only able to control protein

synthesis in a specific or a specific

area okay so if let's say this is the

range that all of them can control they

can only control those domains this is

my nuclear domain theory by fusing more

satellite cells you are now increasing

the range of the domain that you can

cover okay so let's say we got this to

the point where it was it was completely

crowded completely filled up right that

we had enough amount of nuclei that it

was completely filled of space well then

you would be at your your maximum muscle

capacity unless you could fuse a new my

nuclei which would then expand the

amount of muscle protein synthesis it

could control so in this way it appears

that satellite cells control how much

area for muscle protein synthesis can be

controlled and also possibly your

genetic maximum potential for how much

muscle you can naturally gain okay again

each by nuclei controls a certain area

of muscle protein synthesis in order to

get more area and more capacity you'll

need more my own nuclei so some

interesting thoughts to keep in mind I

hope you guys have learned more about

protein synthesis by watching this video

and understand it better feel free to

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