subfamily

1.Pregnane X receptor ( PXR) belongs to NR1 Ⅰ subfamily of the nuclear receptor superfamily(NR).

X受体（PXR）属于核受体超家族（NR）的NR1Ⅰ家族。

2.ADP-ribosylation factors (ARFs), a subfamily of the small GTP binding proteins superfamily, are believed to participate in vesicular transport and signal transduction events in the cell.

棉花纤维的发育需要有高尔基体参与，但ARF基因在棉花纤维发育中的功能尚不清楚。