Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a major nuclear
protein and one of the major components of the hnRNP core complex in m
ammalian cells. We first determined the complete sequence of the human
gene for hnRNP protein A2 (HNRPA2B1). The human HNRPA2B1 gene exists
in a single copy over 9 kb in length. The gene was split into 12 exons
, including a 36-nucleotide mini-exon, which was specific to the hnRNP
protein B1, providing genetic evidence that the B1 mRNA was generated
from the primary HNRPA2B1 transcript by alternative splicing. The 5'
region of HNRPA2B1 was GC-rich and contained several DNA motifs for th
e binding of several transcription factors, which included 2 CCAAT box
es and no TATA sequences. The 5' ends of the mRNA were mapped to multi
ple positions. These structural features are characteristic of promote
r regions of housekeeping genes. Northern blot and RT-PCR analyses of
the HNRPA2B1 transcripts revealed levels of B1 mRNA from 2 to 5% of to
tal A2/B1 transcripts and showed that both A2 and B1 mRNAs were transc
ribed in all human cell lines and mouse tissues studied. The structura
l and evolutionary characteristics of the A2 and A1 proteins as they r
elate to each other are discussed. (C) 1995 Academic Press, Inc.