Department of Biology, Hofstra University, Hempstead, NY 11549, USA.
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Int J Mol Sci. 2023 Dec 27;25(1):392. doi: 10.3390/ijms25010392.
Protein phosphatase 2A (PP2A) functions as a tumor suppressor and consists of a scaffolding, catalytic, and regulatory subunit. The B56 gene family of regulatory subunits impart distinct functions onto PP2A. Codon usage bias (CUB) involves the selection of synonymous codons, which can affect gene expression by modulating processes such as transcription and translation. CUB can vary along the length of a gene, and differential use of synonymous codons can be important in the divergence of gene families. The N-termini of the gene product encoded by B56α possessed high CUB, high GC content at the third codon position (GC3), and high rare codon content. In addition, differential CUB was found in the sequence encoding two B56γ N-terminal splice forms. The sequence encoding the N-termini of B56γ/γ, relative to B56δ/γ, displayed CUB, utilized more frequent codons, and had higher GC3 content. B56α mRNA had stronger than predicted secondary structure at their 5' end, and the B56δ/γ splice variants had long regions of weaker than predicted secondary structure at their 5' end. The data suggest that B56α is expressed at relatively low levels as compared to the other B56 isoforms and that the B56δ/γ splice variant is expressed more highly than B56γ/γ.
蛋白磷酸酶 2A（PP2A）作为一种肿瘤抑制因子，由支架、催化和调节亚基组成。调节亚基的 B56 基因家族为 PP2A 赋予了独特的功能。密码子使用偏性（CUB）涉及同义密码子的选择，这可以通过调节转录和翻译等过程来影响基因表达。CUB 可以沿着基因的长度变化，同义密码子的差异使用在基因家族的分化中可能很重要。B56α 基因产物编码的 N 端具有高 CUB、第三位 GC 含量高（GC3）和稀有密码子含量高。此外，在编码两个 B56γ N 端剪接形式的序列中发现了差异 CUB。与 B56δ/γ 相比，B56γ/γ 的 N 端编码序列显示出 CUB，使用更频繁的密码子，GC3 含量更高。B56α mRNA 在其 5'端具有比预测的二级结构更强的二级结构，而 B56δ/γ 剪接变体在其 5'端具有比预测的二级结构弱的长区域。数据表明，与其他 B56 同工型相比，B56α 的表达水平相对较低，B56δ/γ 剪接变体的表达水平高于 B56γ/γ。
