A cDNA coding for the beta4 Subunit of murine integrin (mbeta4) has be
en cloned and sequenced using mRNA from a murine lung carcinoma as the
template. The 5' sequence contains two AUG codons, the second of whic
h initiates synthesis of the mature protein. The cDNA sequence has an
open reading frame coding for 1748 amino acids (aa), including a signa
l peptide, cysteine-rich region, serine- and threonine-rich region, tr
ansmembrane domain, and a cytoplasmic domain of over 1000 aa. Overall,
the deduced Mbeta4 aa sequence has 88% identity with the human beta4
subunit (hbeta4) sequence deduced from the sequence of placental mRNA.
Reverse transcriptase-polymerase chain reaction using primers flankin
g splice sites for two variant forms of hbeta4 transcripts provided ev
idence for alternate splicing of RNA in the murine spleen and to a les
ser extent in the skin, uterus, and thymus but was found at only one o
f the two alternative sites. Five potential glycosylation sites presen
t in the extracellular domain of hbeta4 are conserved in Mbeta4. One t
yrosine in the terminal region of the cytoplasmic domain (position 160
0) is conserved between Mbeta4 and hbeta4 and has the consensus sequen
ce for tyrosine phosphorylation. Finally, a genomic restriction map of
mbeta4 shows that the gene is about 40 kb in length. No restriction-f
ragment length polymorphisms were detected between BALB/c liver and BA
LB/c lung carcinoma DNA.