VAP proteins are conserved

integral membrane protein An integral, or intrinsic, membrane protein (IMP) is a type of membrane protein that is permanently attached to the biological membrane. All ''transmembrane proteins'' are IMPs, but not all IMPs are transmembrane proteins. IMPs comprise a signi ...

s of the

endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...

found in all

eukaryotic cells Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the ...

. VAP stands for VAMP-associated protein, where VAMP stands for

vesicle-associated membrane protein Vesicle associated membrane proteins (VAMP) are a family of SNARE proteins with similar structure, and are mostly involved in vesicle fusion. * VAMP1 and VAMP2 proteins known as synaptobrevins are expressed in brain and are constituents of th ...

Humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

have two VAPs that consist of the essential Major Sperm Protein domain and linker plus transmembrane helix) to attach to the ER:

VAPA VAMP-Associated Protein A ( or Vesicle-Associated Membrane Protein-Associated Protein A) is a protein that in humans is encoded by the ''VAPA'' gene. Together with VAPB and VAPC it forms the VAP protein family. They are integral endoplasmic retic ...

and

VAPB Vesicle-associated membrane protein-associated protein B/C is a protein that in humans is encoded by the ''VAPB'' gene. The VAPB gene is found on the 20th human chromosome. Together with VAPA, it forms the VAP protein family. Function The ...

. A third VAP-like protein is Motile sperm domain containing 2 (MOSPD2), which has all the elements of VAP, and like them binds FFAT motifs, but has at its N-terminus a

CRAL-TRIO domain CRAL-TRIO domain is a protein structural domain that binds small lipophilic molecules. This domain is named after Retinaldehyde-binding protein 1, cellular retinaldehyde-binding protein (CRALBP) and TRIO (gene), TRIO guanine exchange factor. CRA ...

that can bind and transfer lipids. VAP includes the whole family of protein homologues in all species. For example,

baker's yeast Baker's yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable ...

expresses two VAPs: Scs2 and Scs22.

References

{{Reflist Protein families Single-pass transmembrane proteins