biology

Tyrosine-protein kinase SYK

Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK rather than just read about it. In short: Tyrosine-protein kinase SYK, also known as spleen tyrosine kinase, is an enzyme which in humans is encoded by the SYK gene. Function SYK, along with ZAP70, is a member of the Syk family of tyrosine kinases.

Key takeaways

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

Reference excerpt

Tyrosine-protein kinase SYK, also known as spleen tyrosine kinase, is an enzyme which in humans is encoded by the SYK gene.

Function SYK, along with ZAP70, is a member of the Syk family of tyrosine kinases. These cytoplasmic non-receptor tyrosine kinases share a characteristic dual SH2 domain separated by a linker domain. However, activation of SYK relies less on phosphorylation by Src family kinases than ZAP70. SYK and ZAP70 share a common evolutionary origin and split from a common ancestor in the jawed vertebrates. While Syk and ZAP70 are primarily expressed in hematopoietic tissues, a variety of tissues express Syk. Within B and T cells, respectively, Syk and ZAP70 transmit signals from the B-cell receptor and T-cell receptor. Syk plays a similar role in transmitting signals from a variety of cell surface receptors including CD74, Fc receptor, and integrins.

Function during development Mice that lack Syk completely (Syk−/−, Syk-knockout) die during embryonic development around midgestation. They show severe defects in the development of the lymphatic system. Normally, the lymphatic system and the blood system are strictly separated from each other. However, in Syk deficient mice the lymphatics and the blood vessels form abnormal shunts, leading to leakage of blood into the lymphatic system. The reason for this phenotype was identified by a genetic fate mapping approach, showing that Syk is expressed in myeloid cells which orchestrate the proper separation of lymphatics and blood system during embryogenesis and beyond. Thus, Syk is an essential regulator of the lymphatic system development in mice.

Clinical significance Abnormal function of Syk has been implicated in several instances of hematopoietic malignancies including translocations involving Itk and Tel. Constitutive Syk activity can transform B cells. Several transforming viruses contain "Immunoreceptor Tyrosine Activation Motifs" (ITAMs) which lead to activation of Syk including Epstein–Barr virus, bovine leukemia virus, and mouse mammary tumor virus.

SYK inhibition Given the central role of SYK in transmission of activating signals within B-cells, a suppression of this tyrosine kinase might aid in the treatment of B cell malignancies and autoimmune diseases. Syk inhibition has been proposed as a therapy for both lymphoma and chronic lymphocytic leukemia. Syk inhibitors are in clinical development, including cerdulatinib and entospletinib. Other inhibitors of B-cell receptor (BCR) signaling including ibrutinib (PCI-32765) which inhibits BTK, and idelalisib (PI3K inhibitor - CAL-101 / GS-1101) showed activity in the diseases as well. The orally active SYK inhibitor fostamatinib (R788) in the treatment of immune thrombocytopenia. The Syk inhibitor nilvadipine has been shown to regulate amyloid-β production and Tau phosphorylation and hence has been proposed as a treatment for Alzheimer's disease and has entered phase III clinical trials. The Syk inhibitor sovleplenib is currently in phase 3 trials for warm antibody autoimmune hemolytic anemia (WAIHA).

Epithelial malignancies The role of Syk in epithelial malignancies is controversial. Several authors have suggested that abnormal Syk function facilitates transformation in nasopharyngeal carcinoma and head and neck cancer while other authors have suggested a tumor suppressor role in breast and gastric cancer. Without Syk, the protein it makes, and genetic disruption in a panel of 55 genes thought also to be controlled by Syk, breast ductal carcinoma in situ (breast DCIS, which can become invasive), it is believed that the cancer has a markedly increased tendency to invade and metastasize.

Interactions Syk has been shown to interact with:

Cbl gene CRKL, FCGR2A, FYN, Grb2, Lck, LYN, PTK2, PTPN6, and VAV1.

References

Illustrations

Worked examples

Example 1 — a first encounter with Tyrosine-protein kinase SYK

Start with the simplest possible case. Write down what Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK

In research: Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK 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: Tyrosine-protein kinase SYK is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 9, Tyrosine kinases, so understanding it makes those chapters shorter.
In everyday life: Look for Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tyrosine-protein kinase SYK 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.
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Frequently asked questions

What is Tyrosine-protein kinase SYK in simple terms?

Tyrosine-protein kinase SYK, also known as spleen tyrosine kinase, is an enzyme which in humans is encoded by the SYK gene. Function SYK, along with ZAP70, is a member of the Syk family of tyrosine kinases.

Why does Tyrosine-protein kinase SYK 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 Tyrosine-protein kinase SYK?

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 Tyrosine-protein kinase SYK.