Protein hormones and sex hormones

[beelbe]

Why can sex hormones pass directly into the cell while protein hormones cannot but must attach to the receptor site on the cell membrane?

EDIT: Sorry, I posted in the wrong subforum.

[mith]

protein hormones?

[Dr.Stein]

Why can sex hormones pass directly into the cell while protein hormones cannot but must attach to the receptor site on the cell membrane?

EDIT: Sorry, I posted in the wrong subforum.

Because sex hormones are steroid/lipid so that they will easily diffuse through plasma membrane. Inside the cell, they will be bound to their cytosolic receptor. Meanwhile, protein hormones cannot enter the cell because of their structure, thus they need to bind to their membrane receptor which will activates cascade reaction to bring them in and to take effect(s)

[Revenged]

Why can sex hormones pass directly into the cell while protein hormones cannot but must attach to the receptor site on the cell membrane?

EDIT: Sorry, I posted in the wrong subforum.

Because sex hormones are steroid/lipid so that they will easily diffuse through plasma membrane. Inside the cell, they will be bound to their cytosolic receptor. Meanwhile, protein hormones cannot enter the cell because of their structure, thus they need to bind to their membrane receptor which will activates cascade reaction to bring them in and to take effect(s)

The majority of steroidal receptors are in the nuclues... And have direct effects on silencer/enhancer regions of DNA to decrease/increase production of mRNA and so decrease/increase protein formation...

The only example of a steroids that have cytosolic receptors that I can think of is glucorticoids such as cortisol (hydrocortisone)...

and to add one important thing to remember... cell membrane receptors mediate their responces much more quickly than steroidal receptors...

[Shajjn]

There are probably receptors in the plasma membrane for steroids, aswell - but that's still on reasearch I guess.

[MrMistery]

actually it is a known fact. Most biochemistry and physiology books written in the past few years specify 3 types of receptors for steroid hormones:
1. on the plasma membrane - elictis the fastest response
2. in the cytoplasm
3. in the nucleus.