After T cell receptor (TCR) engagement, the CARD11-Bcl10-Malt1 (CBM) complex oligomerizes to transduce NF-κB activating signals. Bcl10 is then degraded to limit NF-κB activation. The cDNA AK057716 (BinCARD-1) was reported to encode a novel CARD protein that interacts with Bcl10 and modestly inhibits NF-κB activation. In a later study, a second isoform, BinCARD-2, was identified. Here, we report that the cDNA AK057716 (BinCARD-1) is an incompletely spliced derivative of the gene product of C9orf89, whereas CARD19 (BinCARD-2) represents the properly spliced isoform, with conservation across diverse species. Immunoblotting revealed expression of CARD19 in T cells, but no evidence of BinCARD-1 expression, and microscopy demonstrated that endogenous CARD19 localizes to mitochondria. Although we confirmed that both BinCARD-1 and CARD19 can inhibit NF-κB activation and promote Bcl10 degradation when transiently overexpressed in HEK293T cells, loss of endogenous CARD19 expression had little effect on Bcl10-dependent NF-κB activation, activation of Malt1 protease function, or Bcl10 degradation after TCR engagement in primary murine CD8 T cells. Together, these data indicate that the only detectable translated product of C9orf89 is the mitochondrial protein CARD19, which does not play a discernible role in TCR-dependent, Bcl10-mediated signal transduction to Malt1 or NF-κB.

T 细胞受体 (TCR) 结合后，CARD11-Bcl10-Malt1 (CBM) 复合物寡聚化以转导 NF-κB 激活信号。然后 Bcl10 被降解以限制 NF-κB 的激活。据报道，cDNA AK057716 (BinCARD-1) 编码一种新型 CARD 蛋白，该蛋白与 Bcl10 相互作用并适度抑制 NF-κB 活化。在后来的一项研究中，发现了第二种同工型 BinCARD-2。在这里，我们报告 cDNA AK057716 (BinCARD-1) 是C9orf89基因产物的不完全剪接衍生物，而 CARD19 (BinCARD-2) 代表正确剪接的同种型，在不同物种之间具有保护性。免疫印迹显示 CARD19 在 T 细胞中表达，但没有 BinCARD-1 表达的证据，显微镜证明内源性 CARD19 定位于线粒体。尽管我们证实 BinCARD-1 和 CARD19 在 HEK293T 细胞中瞬时过表达时都可以抑制 NF-κB 活化并促进 Bcl10 降解，但内源性 CARD19 表达的丧失对 Bcl10 依赖性 NF-κB 激活、Malt1 蛋白酶功能的激活几乎没有影响，或 Bcl10 在 TCR 参与原代小鼠 CD8 T 细胞后降解。总之，这些数据表明C9orf89唯一可检测的翻译产物 是线粒体蛋白 CARD19，它在 TCR 依赖性、Bcl10 介导的 Malt1 或 NF-κB 信号转导中没有明显作用。