biology

IFITM1

IFITM1 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand IFITM1 rather than just read about it. In short: 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).

Key takeaways

IFITM1 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IFITM1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IFITM1 from memory before moving on to harder problems.

Reference excerpt

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. The first transmembrane domain (TM1) and the cytoplasmic domain are conserved among different IFITM proteins in humans and mice. In the absence of interferon stimulation, IFITM proteins can express broadly in tissues and cell lines. In humans, IFITM1, IFITM2 and IFITM3 are able to express in different tissues and cells while the expression of IFITM5 is limited to osteoblasts. The type I and II interferon induce IFITM proteins expression significantly. IFITM proteins are involved in the physiological process of immune response signaling, germ cell maturation and development.

Biochemistry The gene is induced by interferon and the protein forms part of the signaling pathway.

Antiviral function of IFITM proteins IFITM proteins have been identified as cell-autonomous proteins that suppress the early stages of viral replication. Knockout of IFITM3 increased influenza A virus replication, and overexpression of IFITM3 inhibits influenza virus A replication. In addition to replication competent influenza A virus, IFITM proteins were able to inhibit retrovirus based pseudotyped influenza A virus, indicating that IFITM protein inhibit influenza A virus at the early step of life cycle, may occur in the entry and fusion steps. IFITM proteins also are able to inhibit several infection with other enveloped viruses that belong to different virus families. These virus include flaviviruses (dengue virus and West Nile virus), filoviruses (Marburg virus and Ebola virus), coronaviruses (SARS coronavirus) and lentiviruses (Human Immunodeficiency Virus (HIV)). However, IFITM proteins did not affect alphavirus, arenavirus, or murine leukaemia virus infection. IFITM proteins inhibit viral membrane and cellular endosomal or lysosomal vesicle membrane fusion by modifying their lipid components or fluidity. IFITM proteins block the hemifusion stage of entry, an intermediate stage in which portions the outer membranes of the target cell and the viral envelope mix prior to completion of fusion. Furthermore, IFITM proteins reduced membrane fluidity and affected membrane curvature to restrict viral membrane fusion with the cellular membrane. In addition, IFITM3 interacted with the cellular cholesterol regulatory proteins vesicle associated membrane protein A (VAPA) and oxysterol binding protein (OSBP) to induce intracellular cholesterol accumulation, which in turn blocks viral membrane and vesicle membrane fusion.

References

Illustrations

Worked examples

Example 1 — a first encounter with IFITM1

Start with the simplest possible case. Write down what IFITM1 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to IFITM1 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about IFITM1 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of IFITM1

In research: IFITM1 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses IFITM1 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: IFITM1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clusters of differentiation, Genes on human chromosome 11, so understanding it makes those chapters shorter.
In everyday life: Look for IFITM1 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study IFITM1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IFITM1 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain IFITM1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IFITM1 in simple terms?

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).

Why does IFITM1 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study IFITM1?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on IFITM1.