Whey Acidic Protein
Encyclopedia
Whey Acidic Protein is the major milk protein in certain mammal
s. It has been found in two monotreme
s, three marsupial
s, rodent
s, rabbit
s, pig
s and camel
. Despite extensive studies it has not been found in ruminant
s and humans.
Whey Acidic Protein contains two to three four-disulfide core domain, also termed WAP domain or WAP motif. Each disulfide bond
of the WAP motif is made up of two cysteine
molecule. This motif is also found in other proteins of different functions, which led to the suggestion that WAP is associated with antiprotease or antibacterial properties. The following schematic representation shows the position of the conserved cysteines that form the 'four-disulfide core' WAP domain
+---------------------+
| +-----------+ |
| | | |
xxxxxxxCPxxxxxxxxxCxxxxCxxxxxCxxxxxCCxxxCxxxCxxxx
| | | |
| +--------------+
| |
+----------------------------+
<------------------50-residues------------------>
'C': conserved cysteine involved in a disulfide bond.
It has been found that humans and ruminants have the WAP gene in their genome as pseudogene
. Although humans and ruminants do not seem to encode the gene, there is no detrimental effect. However, mouse pups feeding on maternal milk lacking Whey Acidic Protein has been associated with poor growth rate and lethality
.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. It has been found in two monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
s, three marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s, rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s, pig
Pig
A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
s and camel
Camel
A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as humps on its back. There are two species of camels: the dromedary or Arabian camel has a single hump, and the bactrian has two humps. Dromedaries are native to the dry desert areas of West Asia,...
. Despite extensive studies it has not been found in ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
s and humans.
Whey Acidic Protein contains two to three four-disulfide core domain, also termed WAP domain or WAP motif. Each disulfide bond
Disulfide bond
In chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore R-S-S-R. The terminology is widely used in biochemistry...
of the WAP motif is made up of two cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
molecule. This motif is also found in other proteins of different functions, which led to the suggestion that WAP is associated with antiprotease or antibacterial properties. The following schematic representation shows the position of the conserved cysteines that form the 'four-disulfide core' WAP domain
+---------------------+
| +-----------+ |
| | | |
xxxxxxxCPxxxxxxxxxCxxxxCxxxxxCxxxxxCCxxxCxxxCxxxx
| | | |
| +--------------+
| |
+----------------------------+
<------------------50-residues------------------>
'C': conserved cysteine involved in a disulfide bond.
- WAP-type http://www.expasy.org/prosite/PDOC00026 'four-disulfide core' domain in PROSITEPROSITEPROSITE is a protein database. It consists of entries describing the protein families, domains and functional sites as well as amino acid patterns, signatures, and profiles in them. These are manually curated by a team of the Swiss Institute of Bioinformatics and tightly integrated into Swiss-Prot...
It has been found that humans and ruminants have the WAP gene in their genome as pseudogene
Pseudogene
Pseudogenes are dysfunctional relatives of known genes that have lost their protein-coding ability or are otherwise no longer expressed in the cell...
. Although humans and ruminants do not seem to encode the gene, there is no detrimental effect. However, mouse pups feeding on maternal milk lacking Whey Acidic Protein has been associated with poor growth rate and lethality
Lethality
Lethality is a term designating the ability of a weapon to kill. Most often this term is used when referring to chemical weapons, biological weapons, or their chemical components. The use of this term denotes the ability of these weapons to kill, but also the possibility that they may not kill...
.