Alternatively spliced exons encode the tissue-specific 5' termini of leukocyte pp52 and stromal cell S37 mRNA isoforms.
The pp52 gene encodes an intracellular, F-actin-binding phosphoprotein (also designated LSP1 and WP34) postulated to function in cytoskeleton dynamics and cell motility. We previously reported that different mRNA isoforms are expressed from this gene in cells of the leukocyte lineage versus mesodermally derived cells. These tissue-specific mRNA isoforms are identical except for 5'-untranslated regions and sequences coding for unique N-termini of 23 and 21 amino acids, respectively. As this is a single-copy gene, we predicted that these tissue-specific mRNA isoforms would be generated by alternative RNA splicing. We report that the unique 5' sequences in these mRNA isoforms are encoded in two separate exons containing ATG initiation codons. These features confirm that the pp52 and S37 mRNA isoforms are generated by alternative RNA splicing and establish that they are independently translated. Other results presented here indicate that the differential expression of these exons in leukocytes versus mesodermally derived cells is regulated at the level of transcription by tissue-specific promoters.
Thompson
A A
AA
Department of Pediatrics, UCLA School of Medicine 90095, USA.
Omori
S A
SA
Gilly
M J
MJ
May
W
W
Gordon
M S
MS
Wood
W J
WJ
Miyoshi
E
E
Malone
C S
CS
Gimble
J
J
Denny
C T
CT
Wall
R
R
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D002118:Calcium; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002460:Cell Line; D005091:Exons / Q000235:genetics; D007962:Leukocytes / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D015183:Restriction Mapping; D017154:Stromal Cells / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology
D002135:Calcium-Binding Proteins; C057701:Lsp1 protein, mouse; D008840:Microfilament Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D002118:Calcium