biology

P-selectin glycoprotein ligand-1

P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 rather than just read about it. In short: Selectin P ligand, also known as SELPLG or CD162 (cluster of differentiation 162), is a human gene. SELPLG codes for PSGL-1, the high affinity counter-receptor for P-selectin on myeloid cells and stimulated T lymphocytes.

Key takeaways

P-selectin glycoprotein ligand-1 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect P-selectin glycoprotein ligand-1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of P-selectin glycoprotein ligand-1 from memory before moving on to harder problems.

Reference excerpt

Selectin P ligand, also known as SELPLG or CD162 (cluster of differentiation 162), is a human gene. SELPLG codes for PSGL-1, the high affinity counter-receptor for P-selectin on myeloid cells and stimulated T lymphocytes. As such, it plays a critical role in the tethering of these cells to activated platelets or endothelia expressing P-selectin. Naive and stimulated lymphocytes appear to use PSGL-1 for trafficking into and out of lymph nodes. The gene and protein structure of human PSGL-1 was first discovered in 1993 by Dianne Sako. The research team at Genetics Institute (GI) named the molecule PSGL-1 for "P-selectin glycoprotein ligand-1" although it was found to also bind the other two selectins types. In 1994, the GI team then led by Gray Shaw discovered that most of the binding activity of PSGL-1 was localized within its N-terminal 19 amino acids, including three sulfotyrosines (Tys) at positions 5, 7 and 10 and a critical O-linked glycan attached to the threonine at position 16 of the mature, fully processed PSGL-1 present on a cell's surface. They termed this the "anionic segment" of PSGL-1 in 1995 and then published the co-crystal structure of human PSGL-1's anionic segment bound to human P-selectin in 2000. The organization of the SELPLG gene closely resembles that of CD43 and the human platelet glycoprotein GpIb-alpha both of which have an intron in the 5-prime-noncoding region, a long second exon containing the complete coding region, and TATA-less promoters. P-selectin glycoprotein ligand-1 (PSGL-1) is a dimeric mucin-like glycoprotein found primarily on the surface of white blood cells. PSGL-1 can serve as a ligand for P-selectin (P stands for platelet), which is one of a family of selectins that includes E-selectin (endothelial) and L-selectin (leukocyte). Selectins are part of the broader family of cell adhesion molecules. PSGL-1 can bind to each of the three members of the family but binds best (with the highest affinity) to P-selectin.

Posttranslational modification PSGL-1 protein requires two distinct posttranslational modifications to gain its selectin binding activity:

sulfation of tyrosines the addition of the sialyl Lewis x tetrasaccharide (sLex) to its O-linked glycans

Function PSGL-1 is expressed on all white blood cells and plays an important role in the recruitment of white blood cells into inflamed tissue: White blood cells normally do not interact with the endothelium of blood vessels. However, inflammation causes the expression of cell adhesion molecules (CAM) such as P-selectin on the surface of the blood vessel wall. White blood cells present in flowing blood can interact with CAM. The first step in this interaction process is carried out by PSGL-1 interacting with P-selectin and/or E-selectin on endothelial cells and adherent platelets. This interaction results in "rolling" of the white blood cell on the endothelial cell surface followed by stable adhesion and transmigration of the white blood cell into the inflamed tissue. In 2000 it was reported that PSGL-1 can also be expressed on the surface of platelets, although at a substantially lower level than that seen on the surface of leukocytes.

Clinical significance

In inflammation The systemic administration of soluble recombinant forms of human PSGL-1 such as rPSGL-Ig or TSGL-Ig can prevent reperfusion injury caused by leukocyte influx after an ischemic insult to various types of vascularized tissues (IRI). The protective effects of soluble recombinant forms of PSGL-1, acting as pan-selectin antagonists, has been studied in multiple animal models of solid organ transplant and ARDS.

In cancer In mice PSGL-1 acts as an immune factor regulating multiple T-cell checkpoints. Consequently, the antagonsim of PSGL-1 engagement and signaling has been proposed as a promising target for future checkpoint inhibitor anti-cancer drugs. PSGL-1 has been shown to bind to VISTA (V-domain Ig suppressor of T cell activation) but this binding only occurs under acidic pH conditions (pH < 6.5) such as can be found in tumor microenvironments (TME). In mice, PSGL-1 seems to facilitate T cell exhaustion in tumors. PSGL-1 deficient mice treated with anti-PD-1 antibodies show a dramatic reduction in the growth of melanoma tumors as compared with wild-type mice treated with anti-PD-1 antibodies. Treatments with either soluble recombinant forms of PSGL-1 (PSGL-Ig) or monoclonal antibodies that bind and block PSGL-1 also reduce tumor growth in mouse models, especially when combined with anti-PD-1 monoclonal antibody treatments. It has been noted that the abundant expression of PSGL-1, on the surface of so many different hematopoeitic cell types, causes a target-mediated drug disposition (TMDD) problem or crosslinking problems for antibodies that bind and target PSGL-1. The use of recombinant forms of PSGL-1 avoids the TMDD problem. PSGL-1 is also a phagocytosis ("don't eat me") checkpoint molecule that is distinct from the CD47-SIRPα pathway. Deficiency or antagonism of PSGL-1 on cells (such as hematologic cancer cells) promotes their phagocytosis by macrophages.

References

Illustrations

Worked examples

Example 1 — a first encounter with P-selectin glycoprotein ligand-1

Start with the simplest possible case. Write down what P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1

In research: P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 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: P-selectin glycoprotein ligand-1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Clusters of differentiation, Genes on human chromosome 12, Receptors, so understanding it makes those chapters shorter.
In everyday life: Look for P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is P-selectin glycoprotein ligand-1 in simple terms?

Why does P-selectin glycoprotein ligand-1 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 P-selectin glycoprotein ligand-1?

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 P-selectin glycoprotein ligand-1.