Chapter 2.2.10: Proteins

1. Membrane Proteins.

2. Enzymatic Proteins.

3. DNA Binding/regulatory Proteins.

4. Non-membrane transport Proteins.

5. Structural Proteins.

6. Peptides and peptide hormones.

---

I. Membrane proteins:

One role of proteins in cells is for transport of molecules/ions into or
out of cells. Three methods of doing this are through active, facilitated
or passive transport. Other roles of membrane proteins are in cell recognition,
receptors, cell to cell communication.

Types of Proteins:

Transmembrane Protein:

Globular Protein:

Glyco-protein:
- Glyco-proteins are processed in the Endoplasmic reticulum, and a carbohydrate chain is added on.

A Functional look at Membrane Proteins:

Transport Proteins:

There are two ways that molecules pass through transmembrane proteins:

uniport - which is where one molecule is transported, and
cotransport - where 2 molecules are
transferred.
Also there are two basic types of cotransport:
symport, which is where two molecules
are transported in the same direction and
antiport, where the molecules
are transported opposite directions through the membrane (which will be shown
by the Na - K ATPase pump coming up). Here are the types of transport.

2.1.4.1. Active Transport (these can be either uniport or cotransport):

This transport, which will require energy, is going against
the electro-chemical
gradient. An example of this can be found in the
Na/K ATPase The Sodium-Potassium ATPase pump, this is important especially in the nerves
of all animals. This is commonly used to generate a
membrane potential.

2.1.4.2. Facilitated Transport (these can be either uniport or cotransport):

Facilitated transport is as it sounds, facilitates transport.
This occurs because it moves with the
electro-chemical
gradient.

2.1.4.3. Passive Transport:

Small molecules that are uncharged can move directly through
the membrane in the direction of high concentration to low
concentration. Molecules that have a charge (positive or
negative) it will tend to move to the side of the membrane
that have the opposite electrical potential.

Proteins role in this is through forming channels through
the membrane that facilitate transfer of the molecules
in accordance to the electrical and chemical gradients.

Putting these all together in a membrane is done in the following
example of the Sodium-Potassium
ATPase pump in conjunction with the Potassium leak, and the glucose
symport with Sodium.

Cell Recognition:
Cell recognition occurs through

Cell-Cell Communication:

Receptors:

Enzyme proteins

Binding Proteins:

DNA binding

Non-membrane bound Transport Proteins:

Hormone transport -

Structural Proteins

Peptides and peptide hormones

---

Please send questions/comments/suggestions to: Mark Dalton at markwdalton@gmail.com.