LAMP2

Key takeaways

LAMP2 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LAMP2 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LAMP2 from memory before moving on to harder problems.

Reference excerpt

Lysosome-associated membrane protein 2 (LAMP2), also known as CD107b (Cluster of Differentiation 107b) and Mac-3, is a human gene. Its protein, LAMP2, is one of the lysosome-associated membrane glycoproteins. The protein encoded by this gene is a member of a family of membrane glycoproteins. This glycoprotein provides selectins with carbohydrate ligands. It may play a role in tumor cell metastasis. It may also function in the protection, maintenance, and adhesion of the lysosome. Alternative splicing of the gene produces three variants - LAMP-2A, LAMP-2B and LAMP-2C. LAMP-2A is the receptor for chaperone-mediated autophagy. Recently it has been determined that antibodies against LAMP-2 account for a fraction of patients who get a serious kidney disease termed focal necrotizing glomerulonephritis. LAMP-2B is associated with Danon disease.

Structure and tissue distribution The gene for LAMP2 has 9 coding exons and 2 alternate last exons, 9a and 9b. When the last exon is spliced with the alternative exon, it is a variant called LAMP2b, which varies in the last 11 amino acids of its C-terminal sequence: in the luminal domain, the transmembrane domain, and the cytoplasmic tail. The original (LAMP2a) is highly expressed in the placenta, lung, and liver, while LAMP2b is highly expressed in skeletal muscle.

Function Lysosomes are cell organelles found in most animal cells. Their main functions center around breaking down materials and debris in the cell. Some of this is done via acid hydrolases that degrade foreign materials and have specialized autolytic functions. These hydrolyses are stored in the lysosomal membrane, which also house lysosomal membrane glycoproteins. LAMP1 and LAMP2 make up about 50% of lysosomal membrane glycoproteins. (See LAMP1 for more information on both LAMP1 and LAMP2.) Both of these consist of polypeptides of about 40 kD, with the core polypeptide surrounded by 16 to 20 attached N-linked saccharides. The biological functions of these glycoproteins are disputed. They are believed to be significantly involved in operations of the lysosomes, including maintaining integrity, pH and catabolism. Further, some of the functions of LAMP2 are believed to be protecting the lysosomal membrane from proteolytic enzymes that are within the lysosome itself (as in autodigestion), acting as a receptor into the lysosome for proteins, adhesion (when expressed on the outside surface of the plasma membrane) and signal transduction, both inter- and intra-. It also provides protection for the cell from methylating mutagens.

Role in cancer LAMP2 has been specifically implicated in tumor cell metastasis. Both LAMP1 and LAMP2 have been found expressed on the surface of cancerous tumors, specifically in cells of highly metastatic cancer such as colon cancer and melanoma. They are rarely found on the plasma membranes of normal cells, and are found more on highly metastatic tumors than on poorly metastatic ones. LAMP2, along with LAMP1, interact with E-selectin and galectins to mediate the adhesion of some cancer cells to the ECM. The two LAMP molecules act as ligands for the cell-adhesion molecules. It has also been shown that the down-regulation of LAMP2 could both reduce the resistance of breast cancer cells to the paclitaxel and could inhibit cell proliferation in multiple myeloma cells. Along with other genes such as LC3B, p62 and CTSB, a strong up regulation of LAMP2 was detected in perinecrotic areas of glioblastomas. This suggests autophagy induction in gliomas could be caused by micro-environmental changes. In a study of glial tumors, the cell membranes of glial and endothelial cells were found to contain LAMP1 and LAMP2, while YKL-40 (a different glycoprotein) was found in the cytoplasm. This suggests that the three glycoproteins are involved in tumor development, specifically in the processes of angiogenesis and tissue remodeling.

Inducers CA77.1 QX39

Illustrations

Worked examples

Example 1 — a first encounter with LAMP2

Start with the simplest possible case. Write down what LAMP2 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 LAMP2 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 LAMP2 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 LAMP2

In research: LAMP2 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 LAMP2 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: LAMP2 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clusters of differentiation, Genes on human chromosome X, so understanding it makes those chapters shorter.
In everyday life: Look for LAMP2 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 LAMP2 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LAMP2 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 LAMP2 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LAMP2 in simple terms?

Lysosome-associated membrane protein 2 (LAMP2), also known as CD107b (Cluster of Differentiation 107b) and Mac-3, is a human gene. Its protein, LAMP2, is one of the lysosome-associated membrane glycoproteins.

Why does LAMP2 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 LAMP2?

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 LAMP2.