ABCA12
Encyclopedia
ATP-binding cassette sub-family A member 12 also known as ATP-binding cassette transporter 12 is a protein
that in humans is encoded by the ABCA12 gene
.
ABCA12 belongs to a group of genes called the ATP-binding cassette family
, which makes proteins that transport molecules across cell membrane
s. The ABCA12 gene is active in some types of skin cells and in several other tissues, such as testis, placenta
, lung
, stomach
, and fetal brain and liver. The ABCA12 protein appears to be essential for normal development of the skin
, which provides a barrier between the body and its surrounding environment. Although the exact function of the protein is unknown, researchers suggest that it probably plays an important role in transporting lipid
s (fats) in cells that make up the outermost layer of skin (the epidermis).
The ABCA12 gene is located on the long (q) arm of chromosome 2
between positions 34 and 35, from base pair
215,621,772 to base pair 215,828,656.
s in the ABCA12 gene are known to cause harlequin type ichthyosis
. Most of these mutations are predicted to lead to an absence of ABCA12 protein or the production of an extremely small version of the protein that cannot transport lipids properly. A loss of functional ABCA12 protein causes numerous problems with the development of the epidermis before and after birth. Abnormalities in lipid transport prevent the skin from forming an effective barrier and result in the hard, thick scales characteristic of harlequin ichthyosis.
Mutations in the ABCA12 gene also cause another severe skin disorder, lamellar ichthyosis type 2. People with this disorder have red, scaly, plate-like skin covering most of their bodies. The ABCA12 mutations that cause this disorder substitute one amino acid
(a building block of proteins) for another amino acid in the ABCA12 protein. These mutations almost always occur in an important functional region of the protein (the region that binds to ATP
, a molecule that supplies energy for chemical reactions). Changes in the structure of the ABCA12 protein likely disrupt its ability to transport lipids, which affects the development of skin before and after birth.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the ABCA12 gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
ABCA12 belongs to a group of genes called the ATP-binding cassette family
ATP-binding cassette family
The ATP-binding cassette family is a group of proteins which bind and hydrolyse ATP in order to transport substances across cellular membranes...
, which makes proteins that transport molecules across cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
s. The ABCA12 gene is active in some types of skin cells and in several other tissues, such as testis, placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
, lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
, stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
, and fetal brain and liver. The ABCA12 protein appears to be essential for normal development of the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, which provides a barrier between the body and its surrounding environment. Although the exact function of the protein is unknown, researchers suggest that it probably plays an important role in transporting lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s (fats) in cells that make up the outermost layer of skin (the epidermis).
The ABCA12 gene is located on the long (q) arm of chromosome 2
Chromosome 2 (human)
Chromosome 2 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second largest human chromosome, spanning more than 237 million base pairs and representing almost 8% of the total DNA in cells.Identifying genes on each...
between positions 34 and 35, from base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
215,621,772 to base pair 215,828,656.
Related conditions
Several mutationMutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s in the ABCA12 gene are known to cause harlequin type ichthyosis
Harlequin type ichthyosis
Harlequin-type ichthyosis , a skin disease, is the most severe form of congenital ichthyosis, characterized by a thickening of the keratin layer in fetal human skin...
. Most of these mutations are predicted to lead to an absence of ABCA12 protein or the production of an extremely small version of the protein that cannot transport lipids properly. A loss of functional ABCA12 protein causes numerous problems with the development of the epidermis before and after birth. Abnormalities in lipid transport prevent the skin from forming an effective barrier and result in the hard, thick scales characteristic of harlequin ichthyosis.
Mutations in the ABCA12 gene also cause another severe skin disorder, lamellar ichthyosis type 2. People with this disorder have red, scaly, plate-like skin covering most of their bodies. The ABCA12 mutations that cause this disorder substitute one amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
(a building block of proteins) for another amino acid in the ABCA12 protein. These mutations almost always occur in an important functional region of the protein (the region that binds to ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
, a molecule that supplies energy for chemical reactions). Changes in the structure of the ABCA12 protein likely disrupt its ability to transport lipids, which affects the development of skin before and after birth.