biology

LRRIQ3

LRRIQ3 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 LRRIQ3 rather than just read about it. In short: LRRIQ3 (Leucine-rich repeats and IQ motif containing 3), which is also known as LRRC44, is a protein that in humans is encoded by the LRRIQ3 gene. It is predominantly expressed in the testes, and is linked to a number of diseases.

Key takeaways

LRRIQ3 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LRRIQ3 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LRRIQ3 from memory before moving on to harder problems.

Reference excerpt

LRRIQ3 (Leucine-rich repeats and IQ motif containing 3), which is also known as LRRC44, is a protein that in humans is encoded by the LRRIQ3 gene. It is predominantly expressed in the testes, and is linked to a number of diseases.

Gene

Locus LRRIQ3 is found on the minus strand of the end of the short arm of human chromosome 1 at 1p31.1.

Overall Structure There are a total of 7 exons in the putative sequence of LRRIQ3.

mRNA

Expression LRRIQ3 is expressed as 2 primary isoforms, which produce proteins of length 624 amino acids and 464 amino acids respectively. It is expressed at low levels in human and brown rat tissues, with highest expression levels in testes tissue. There are relatively high expression levels in T cells, the epididymis, the kidney, and a number of glands.

Protein

General Characteristics and Compositional Features Human protein LRRIQ3 Isoform 1 consists of 624 amino acids, and has a molecular weight of 73.7 kDa. The isoelectric point of LRRIQ3 is 9.73, which suggests that LRRIQ3 is basic at normal physiological pH (~7.4). Additionally, there is strong evidence that human LRRIQ3 localizes to the plasma membrane from antibody staining. LRRIQ3 is rich in lysine residues, with a total of 82 lysines. It is also slightly low on glycines.

Domains and Motifs In total, there are 4 conserved domains within LRRIQ3: 3 leucine-rich repeats and 1 IQ calmodulin-binding motif. Leucine-rich repeats are typically involved in protein-protein interactions, and form a characteristic α/β horseshoe fold. An IQ motif provides a binding site for calmodulin (CaM) or CaM-like proteins.

Secondary and Tertiary Structure LRRIQ3 is predicted to be mostly alpha-helical in structure, including a long alpha-helical C-terminal domain. It is also predicted to function as a monomer.

Post-translational Modifications LRRIQ3 is predicted to undergo many post-translational modifications. These include O-GlcNAcylation, SUMOylation, ubiquitination, and phosphorylation. LRRIQ3 is predicted to have 4 well conserved SUMOylation sites and 1 well conserved ubiquitination site. A representation of these post-translational modifications is shown in the figure below.

Protein Interactions There is evidence that LRRIQ3 interacts with a number of proteins from two-hybrid assays and affinity chromatography. The proteins LRRIQ3 interact with include LYN, NCK2, GNB4, and ABL1. These proteins are associated with cell signalling, cytoskeletal reorganization, and cell differentiation, as well as others.

Homology and evolution

Paralogs and Orthologs No paralogs exists for LRRIQ3 in humans. However, there are a number of orthologs, as reported by BLAST, some of which are listed below. The number of years since divergence from the human protein, listed in "million of years ago (MYA)" below, were calculated using TimeTree.

Clinical significance LRRIQ3 is linked to a number of cancers. RNA-seq experiments have shown that LRRIQ3 is severely down-regulated (Log2-fold changes between -3.4 and -4.2) in a number of disease states, including pancreatic cancer, colorectal cancer, and breast cancer.

References

Illustrations

Worked examples

Example 1 — a first encounter with LRRIQ3

Start with the simplest possible case. Write down what LRRIQ3 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 LRRIQ3 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 LRRIQ3 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 LRRIQ3

In research: LRRIQ3 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 LRRIQ3 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: LRRIQ3 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Genes on human chromosome 1, Proteins, so understanding it makes those chapters shorter.
In everyday life: Look for LRRIQ3 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 LRRIQ3 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LRRIQ3 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 LRRIQ3 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LRRIQ3 in simple terms?

Why does LRRIQ3 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 LRRIQ3?

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 LRRIQ3.