IFITM1
Description
The IFITM1 (interferon induced transmembrane protein 1) is a protein-coding gene located on chromosome 11.
Interferon-induced transmembrane protein 1 is a protein that in humans is encoded by the IFITM1 gene. IFITM1 has also recently been designated CD225 (cluster of differentiation 225). This protein has several additional names: fragilis (human homolog of the mouse protein), IFI17 [interferon-induced protein 17], 9-27 [Interferon-inducible protein 9-27] and Leu13. IFITM1 is a member of the IFITM family (Interferon-induced transmembrane protein) which is encoded by IFITM genes. The human IFITM genes locate on chromosome 11 and have four members: IFITM1, IFITM2, IFITM3 and IFITM5. While the mouse Ifitm genes locate on chromosome 7 and 16 and have six members: Ifitm1, Ifitm2, Ifitm3, Ifitm5, Ifitm6 and Ifitm7.
== Molecular biology == The IFITM1 gene is located on the Watson (plus) strand of the short arm of chromosome 11 (11p15.5) and is 3,956 bases in length. The encoded protein has 125 amino acids (molecular weight 13.964 kDa). It is an intrinsic membrane protein and is predicted to cross the membrane several times.
== Structure and function == IFITM proteins have a short N-terminal and C-terminal domain, two transmembrane domains (TM1 and TM2) and a short cytoplasmic domain.
IFITM1 is an interferon-induced antiviral protein that prevents viruses from entering the host cell cytoplasm. It allows viruses to be taken up by the cell through endocytosis, but then stops the viruses from fusing with the cell membrane and releasing their contents into the cell. This action protects the cell from infection by a variety of viruses, including influenza A virus, SARS coronaviruses (SARS-CoV and SARS-CoV-2), Marburg virus (MARV), Ebola virus (EBOV), Dengue virus (DNV), West Nile virus (WNV), human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV). IFITM1 specifically inhibits the entry of these viruses by blocking the activity of their entry proteins, such as the influenza virus hemagglutinin protein, MARV and EBOV GP1,2, and SARS-CoV and SARS-CoV-2 S protein. In addition to its antiviral activity, IFITM1 is also involved in cell adhesion, cell growth, and cell migration. It inhibits the formation of syncytia (fusion of cells) caused by the SARS-CoV-2 S protein. IFITM1 also plays a role in the antiproliferative action of IFN-gamma, possibly by inhibiting ERK activation or arresting cell growth in the G1 phase in a p53-dependent manner. It acts as a positive regulator of osteoblast differentiation. In hepatocytes, IFITM1 works with other IFITM proteins to prevent HCV infection by directing the endocytosed HCV virion to the lysosome for degradation. IFITM2 and IFITM3 also contribute to anti-HCV activity, possibly by inhibiting the late stages of HCV entry and targeting the virion for degradation in the lysosome. IFITM1 interacts with CD81 and is part of a complex with CD19, CR2/CD21, CD81, and IFITM1/CD225 in the membrane of mature B-cells. It also interacts with CAV1, which enhances CAV1's ability to inhibit ERK activation.
IFITM1 is also known as 9-27, CD225, DSPA2a, IFI17, LEU13.
