# DBT JRF 2022 — Question 34

Exam: DBT JRF 2022 · Section: B · Topic: Cell Biology › Chromatin & Histone Variants · Difficulty: Medium

## Question

A specialized histone associated with the centromeric region of the chromosome is:

## Options

- **A.** CenH3
- **B.** H2A.Z
- **C.** H3.3
- **D.** H2A.X

## Answer

Option A

## Explanation

CenH3: centromere-specific histone variant: CenH3 (also called CENP-A in humans, CID in Drosophila) is a specialized histone H3 variant with a unique N-terminal tail and distinct CATD (CENP-A Targeting Domain) in the histone fold domain. Functions: • Specifically deposited at centromeric chromatin (replacing canonical H3). • Forms a centromeric nucleosome that serves as the epigenetic mark defining the centromere. • Recruits other CCAN (Constitutive Centromere-Associated Network) proteins. • Provides the platform for kinetochore assembly, which connects chromosomes to spindle microtubules during mitosis. Key: The location of centromeres is specified EPIGENETICALLY by CenH3, not by a specific DNA sequence in most organisms. Answer: CenH3 (CENP-A) is deposited at centromeric regions to define the kinetochore assembly platform.

Source: https://mypyqbuddy.com/questions/a-specialized-histone-associated-with-the-centromeric-region-6a104cd5920734408bc0c731