biology

Testis-enhanced gene transfer family

Testis-enhanced gene transfer family 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 Testis-enhanced gene transfer family rather than just read about it. In short: The testis-enhanced gene transcript (TEGT) family includes the testis-enhanced gene transcript proteins of mammals, which are expressed at high levels in the testis, the putative glutamate/aspartate binding proteins of plants and animals, the YccA protein of Escherichia coli and the YetJ protein of Bacillus subtilis. These proteins are about 200-250 residues in length and exhibit 7 TMSs.

Key takeaways

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Reference excerpt

The testis-enhanced gene transcript (TEGT) family includes the testis-enhanced gene transcript proteins of mammals, which are expressed at high levels in the testis, the putative glutamate/aspartate binding proteins of plants and animals, the YccA protein of Escherichia coli and the YetJ protein of Bacillus subtilis. These proteins are about 200-250 residues in length and exhibit 7 TMSs.

Homology Homologues are found in a variety of Gram-negative and Gram-positive bacteria, yeast, fungi, plants, animals and viruses. The E. coli genome encodes three paralogues, YbhL, YbhM and YccA. Distant homologues found in Drosophilia melanogaster and the rat are the N-methyl-D-aspartate receptor-associated protein (NMDARAI) and the N-methyl-D-aspartate receptor glutamate binding chain, respectively. Two others are the rat neural membrane protein 35 and the Arabidopsis thaliana Bax inhibitor-1 (BI-1) protein capable of suppressing Bax-induced cell death in yeast.

BI-1 One of these proteins, TEGT or the Bax Inhibitor-1 (TC# 1.A.14.1.1), has a C-terminal domain that forms a Ca2+-permeable channel. BI-1 is an ER-localized protein that protects against apoptosis and ER stress. BI-1 has been proposed to modulate ER Ca2+ homeostasis by acting as a Ca2+-leak channel. These proteins are distantly related to the ionotropic glutamate-binding protein of the N-methyl D-aspartate (NMDA) receptor of man. Homologues include a putative cold shock inducible protein and a SecY stabilizing protein.

Function Based on experimental determination of the BI-1 topology, Bultynck et al. proposes that its C-terminal α-helical 20 amino acid peptide catalyzes Ca2+ flux both in vivo and in vitro. The Ca2+-leak properties were conserved among animal, but not plant and yeast orthologs. By mutating one of the critical aspartate residues (D213) in the proposed Ca2+-channel pore in full-length BI-1, D213 proved to be essential for BI-1 dependent ER Ca2+-leak.

Structure Chang et al. published crystal structures of a bacterial homolog, YetJ (TC# 1.A.14.2.3) at 1.9 Å resolution and characterized its calcium leak activity. Its seven-transmembrane-helix fold features two triple-helix sandwiches wrapped around a central C-terminal helix. Structures obtained in closed and open conformations are reversibly interconvertible by changes in the pH. A hydrogen-bonded perturbed pair of conserved aspartyl residues explains the pH dependence of this transition, and the pH regulates calcium influx in proteoliposomes. Homology models for human BI-1 provided insight into its cytoprotective activity.

Transport Reaction The generalized reaction catalyzed by TEGT channels is:

cations (out) ⇌ cations (in)

References

As of this edit, this article uses content from "1.A.14 The Testis-Enhanced Gene Transfer (TEGT) Family", which is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License, but not under the GFDL. All relevant terms must be followed.

Worked examples

Example 1 — a first encounter with Testis-enhanced gene transfer family

Start with the simplest possible case. Write down what Testis-enhanced gene transfer family 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 Testis-enhanced gene transfer family 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 Testis-enhanced gene transfer family 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 Testis-enhanced gene transfer family

In research: Testis-enhanced gene transfer family 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 Testis-enhanced gene transfer family 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: Testis-enhanced gene transfer family is common in secondary-school and first-year university syllabi. It links to neighbouring topics Integral membrane proteins, Membrane proteins, Protein families, so understanding it makes those chapters shorter.
In everyday life: Look for Testis-enhanced gene transfer family 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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Frequently asked questions

What is Testis-enhanced gene transfer family in simple terms?

Why does Testis-enhanced gene transfer family 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.

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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.

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