SLAMF1

Key takeaways

SLAMF1 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SLAMF1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SLAMF1 from memory before moving on to harder problems.

Reference excerpt

Signaling lymphocytic activation molecule 1 is a protein that in humans is encoded by the SLAMF1 gene. Recently SLAMF1 has also been designated CD150 (cluster of differentiation 150). SLAMF1 belongs to the signaling lymphocytic activation molecule family. As other receptors from this family, SLAMF1 is expressed in different types of hematopoietic cells and it plays a role in the regulation of the immune system.

Gene The gene encoding SLAMF1 receptor is located on the human chromosome 1. It consists of eight exons and seven introns. Alternative splicing of SLAMF1 transcripts results in several isoforms of the protein, including the conventional transmembrane isoform (mCD150), secreted isoform (sCD150) cytoplasmic isoform (cCD150), and the novel transmembrane isoform (nCD150). SLAMF1 is expressed in hematopoietic stem cells. It is also used as one of the markers for their identification. Furthermore, its expression was detected in thymocytes, NKT cells, T cells, B cells, monocytes, macrophages and dendritic cells. Monocytes, macrophages and dendritic cells express SLAMF1 after their activation. The activation of T cells and plasma cell differentiation leads to the increased expression of this receptor. The interaction of SLAMF1 promoter and enhancers with the Early B-cell factor 1 (EBF1) is required for the expression of SLAMF1 gene in B cells. STAT6, IRF4, and NF-kB factors involved in the transfer of the signals from the B-cell receptor, its co-receptors and IL-4R, also play important role in the regulation of SLAMF1 expression. The expression of SLAMF1 is not restricted to immune cells and their progenitors. From non-immune cells, platelets express SLAMF1.

Structure SLAMF1 is a type I transmembrane protein belonging to the immunoglobulin superfamily. Its molecular weight is between 70 kDa and 95 kDa. The extracellular region of the receptor is composed of one Ig variable-like domain and one Ig constant 2-like domain. The intracellular region of the receptor contains two intracellular tyrosine-based switch motives (ITSMs) that interact with SH2 domain-containing proteins. However, nCD150 intracellular region differs from other isoforms of this protein, it lacks ITSMs. sCD150 isoform lacks the transmembrane domain and therefore, it can not be anchored to the cell membrane.

Signaling The receptor SLAMF1 mediates homophilic interactions as most of the receptors from the SLAMF. Signaling from SLAMF1 receptor can be activating or inhibitory. The type of the signal depends on the cell type, differentiation stage, and the combination of signals from other receptors. SH2 domain-containing proteins, specifically adaptor proteins SAP and EAT-2, and phosphatases SHP-1, SHP-2 and SHIP, interact with ITSMs in the intracellular region of SLAMF1. Binding of SAP to ITSMs leads to the activation of the kinase Fyn that phosphorylates tyrosines of SLAMF1 and recruits downstream signaling proteins. Because of the high affinity of SAP to tyrosine phosphorylated ITSMs, it outcompetes the phosphatases which are the mediators of the inhibitory signal. Therefore, the expression and availability of SAP play a crucial role in the determination of the type of the signal.

Function SLAMF1 is involved in the regulation of thymocyte development, T cell proliferation, differentiation and T cell function, such as the cytotoxic activity of CD8+ T cells and the production of IL-4, IL-13 and IFNγ. In B cells, it regulates the proliferation and the antibody production. SLAMF1 acts as a self-ligand during the interaction between B cells and T cells and promotes lymphocyte activation. The development of NKT cells is dependent on a signal mediated by SAP. It was found out that the homophilic interaction of SLAMF1 or SLAMF6 is required for SAP recruitment in NKT cells. This interaction mediates a secondary signal crucial for NKT cell differentiation and expansion in the thymus. SLAMF1 expression in macrophages is associated with killing of Gram-negative bacteria. SLAMF1 acts as a bacterial sensor. It is internalized after the recognition of Gram-negative bacteria, and it plays a role in the regulation of phagosome maturation, ROS and NO production. The absence of SLAMF1 in phagocytes leads, among other things, to the disruption of cytokine production.

Role of SLAMF1 in diseases

Viral infections SLAMF1 is a receptor for Morbilliviruses. This genus of viruses includes agents causing measles in humans, rinderpest in cattle and distemper in dogs and cats. Ig variable-like domain of SLAMF1 binds to hemagglutinin on the surface of the virus and this interaction mediates the virus entry into the host cell.

Cancer SLAMF1 is expressed in cancer cells in some types of hematologic malignancies (cutaneous T-cell lymphoma, few types of B-cell non-Hodgkin´s lymphoma, Hodgkin´s lymphoma and about 50 % of chronic lymphocytic leukemia cases). It regulates cancer cell growth and survival by activating PI3K/Akt/mTOR signaling pathway. Therefore, SLAMF1 could be used as a diagnostical and prognostic marker in these cancer types. Several cases of leukemia or Hodgkin´s lymphoma remission after measles virus infection or vaccination have been described. Therefore, SLAMF1 could be used as a target for cancer therapy which is based on the measles virus-mediated lysis of the cancer cells. nCD150 isoform was found in tumors of the central nervous system, such as glioblastoma, anaplastic and diffuse astrocytoma and ependymoma.

References

Illustrations

Worked examples

Example 1 — a first encounter with SLAMF1

Start with the simplest possible case. Write down what SLAMF1 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 SLAMF1 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 SLAMF1 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 SLAMF1

In research: SLAMF1 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 SLAMF1 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: SLAMF1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clusters of differentiation, Genes on human chromosome 1, so understanding it makes those chapters shorter.
In everyday life: Look for SLAMF1 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.

How to study SLAMF1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SLAMF1 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 SLAMF1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SLAMF1 in simple terms?

Signaling lymphocytic activation molecule 1 is a protein that in humans is encoded by the SLAMF1 gene. Recently SLAMF1 has also been designated CD150 (cluster of differentiation 150).

Why does SLAMF1 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 SLAMF1?

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 SLAMF1.