biology

Lactosylceramide alpha-2,3-sialyltransferase

Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase rather than just read about it. In short: In enzymology, a lactosylceramide alpha-2,3-sialyltransferase (EC 2.4.99.9) is an enzyme that catalyzes the chemical reaction CMP-N-acetylneuraminate + beta-D-galactosyl-1,4-beta-D-glucosylceramide ⇌ {\displaystyle \rightleftharpoons } CMP + alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D- glucosylceramide Thus, the two substrates of this enzyme are CMP-N-acetylneuraminate and beta-D-galactosyl-1,4-beta-D…

Key takeaways

Lactosylceramide alpha-2,3-sialyltransferase belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lactosylceramide alpha-2,3-sialyltransferase to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lactosylceramide alpha-2,3-sialyltransferase from memory before moving on to harder problems.

Reference excerpt

In enzymology, a lactosylceramide alpha-2,3-sialyltransferase (EC 2.4.99.9) is an enzyme that catalyzes the chemical reaction

CMP-N-acetylneuraminate + beta-D-galactosyl-1,4-beta-D-glucosylceramide ⇌ {\displaystyle \rightleftharpoons } CMP + alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D- glucosylceramide Thus, the two substrates of this enzyme are CMP-N-acetylneuraminate and beta-D-galactosyl-1,4-beta-D-glucosylceramide, whereas its 3 products are CMP, alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D-, and glucosylceramide. This enzyme belongs to the family of transferases, specifically those glycosyltransferases that do not transfer hexosyl or pentosyl groups. The systematic name of this enzyme class is CMP-N-acetylneuraminate:lactosylceramide alpha-2,3-N-acetylneuraminyltransferase. Other names in common use include cytidine monophosphoacetylneuraminate-lactosylceramide alpha2,3-, sialyltransferase, CMP-acetylneuraminate-lactosylceramide-sialyltransferase, CMP-acetylneuraminic acid:lactosylceramide sialyltransferase, CMP-sialic acid:lactosylceramide-sialyltransferase, cytidine monophosphoacetylneuraminate-lactosylceramide, sialyltransferase, ganglioside GM3 synthetase, GM3 synthase, GM3 synthetase, and SAT 1. This enzyme participates in glycosphingolipid biosynthesis - ganglioseries and glycan structures - biosynthesis 2.

Structural studies As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes PDB: 2EX0 and PDB: 2EX1.

Function Ganglioside GM3 is known to participate in the induction of cell differentiation, modulation of cell proliferation, maintenance of fibroblast morphology, signal transduction, and integrin-mediated cell adhesion. The enzyme is a type II membrane protein which catalyzes the formation of GM3 using lactosylceramide as the substrate. The encoded protein is a member of glycosyltransferase family 29 and may be localized to the Golgi apparatus. Mutation in this gene has been associated with Amish infantile epilepsy syndrome. Transcript variants encoding different isoforms have been found for this gene.

Gene

Lactosylceramide alpha-2,3-sialyltransferase is encoded in humans by the ST3GAL5 gene. Mutations in this gene have also been associated to ‘Salt & Pepper’ syndrome: an autosomal recessive condition characterized by severe intellectual disability, epilepsy, scoliosis, choreoathetosis, dysmorphic facial features and altered dermal pigmentation. (doi: 10.1093/hmg/ddt434)

References

Bibliography Basu S, Kaufman B, Roseman S (1973). "Enzymatic synthesis of glucocerebroside by a glucosyltransferase from embryonic chicken brain". J. Biol. Chem. 248 (4): 1388–94. doi:10.1016/S0021-9258(19)44311-1. PMID 4631392. Fishman PH, Bradley RM, Henneberry RC (1976). "Butyrate-induced glycolipid biosynthesis in HeLa cells: properties of the induced sialyltransferase". Arch. Biochem. Biophys. 172 (2): 618–26. doi:10.1016/0003-9861(76)90116-8. PMID 4022. Higashi H, Basu M, Basu S (1985). "Biosynthesis in vitro of disialosylneolactotetraosylceramide by a solubilized sialyltransferase from embryonic chicken brain". J. Biol. Chem. 260 (2): 824–8. doi:10.1016/S0021-9258(20)71172-5. PMID 3838172.

Worked examples

Example 1 — a first encounter with Lactosylceramide alpha-2,3-sialyltransferase

Start with the simplest possible case. Write down what Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase

In research: Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase 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: Lactosylceramide alpha-2,3-sialyltransferase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 2.4.99, EC 2.4 stubs, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lactosylceramide alpha-2,3-sialyltransferase means in your own words.
Compare your version with the excerpt and mark what you missed.
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Frequently asked questions

What is Lactosylceramide alpha-2,3-sialyltransferase in simple terms?

In enzymology, a lactosylceramide alpha-2,3-sialyltransferase (EC 2.4.99.9) is an enzyme that catalyzes the chemical reaction CMP-N-acetylneuraminate + beta-D-galactosyl-1,4-beta-D-glucosylceramide ⇌ {\displaystyle \rightleftharpoons } CMP + alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,4-beta-D…

Why does Lactosylceramide alpha-2,3-sialyltransferase 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 Lactosylceramide alpha-2,3-sialyltransferase?

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 Lactosylceramide alpha-2,3-sialyltransferase.