PMID- 10625438
OWN - NLM
STAT- MEDLINE
DCOM- 20000127
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 38
IP  - 48
DP  - 1999 Nov 30
TI  - Brain and muscle express a unique alternative transcript of alphaII spectrin.
PG  - 15721-30
AB  - Alternative splicing of pre-mRNA transcripts of alpha and beta spectrin has
      emerged as an important generator of diversity in this gene family, yet the
      functional consequences and extent of this diversity remains unknown. We have
      cloned and characterized full-length alphaII spectrin cDNA from human fetal brain
      (GenBank and ). On the basis of the predicted amino acid sequence, 11 amino acid 
      substitutions, presumably representing polymorphisms, have been identified that
      distinguish this alphaII spectrin from human lung fibroblast alphaII spectrin. In
      addition, human fetal brain spectrin displays a novel five amino acid insertion
      in repeat 15 that arises from alternative mRNA splicing and that distinguishes
      this spectrin from lung fibroblast alphaII++ spectrin. This discovery, together
      with two previously identified regions of alternative mRNA splicing in alphaII
      spectrin suggest that as many as eight different splice forms of the mature
      protein might exist if all combinations (at inserts 1, 2, and 3) of alternative
      mRNA splicing are utilized. To assess this possibility, the tissue distribution
      of alternative exon usage was investigated by semiquantitative PCR with
      intron-jumping primer sets. Tissues examined were from mouse and included heart, 
      kidney, lung, liver, thymus, spleen, brain, ovary, testis, and skeletal muscle,
      as well as mouse embryonic tissue. Transcripts both with and without insert 1,
      representing a 60 bp insertion within alphaII spectrin repeat 10, were identified
      in all tissues. In contrast, transcripts with insert 2, the novel 15 bp insertion
      reported here, were only expressed in brain, heart, skeletal muscle, and
      embryonic tissue. In all tissues examined only transcripts positive for insert 3,
      an 18 bp insertion in repeat 21, were amplified, even under conditions in which a
      30% level of insert 3 negative transcript could be easily detected in
      artificially prepared control samples. All combinations of insert 1 and insert 2 
      were identified together in individual transcripts, verifying at least four
      distinct isoforms of alphaII spectrin. These have been named alphaIISigma1
      through alphaIISigma4, in accord with current spectrin naming conventions.
      Dynamic molecular modeling of the 15th repeat unit incorporating insert 2
      predicts that the spliced sequence forms a loop between helices A and B, and
      suggests that this insert might constitute a novel protein interaction site. The 
      presence of this sequence in alphaIISigma3 and alphaIISigma4 spectrin suggests a 
      specialized and heretofore unanticipated function for the 15th repeat of this
      molecule.
FAU - Cianci, C D
AU  - Cianci CD
AD  - Department of Pathology, and the Department of Molecular, Cellular and
      Developmental Biology, Yale University, 310 Cedar Street, New Haven, Connecticut 
      06510, USA.
FAU - Zhang, Z
AU  - Zhang Z
FAU - Pradhan, D
AU  - Pradhan D
FAU - Morrow, J S
AU  - Morrow JS
LA  - eng
SI  - GENBANK/U26396
SI  - GENBANK/U83867
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (DNA, Complementary)
RN  - 0 (Protein Isoforms)
RN  - 12634-43-4 (Spectrin)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Brain/embryology/*metabolism
MH  - Cloning, Molecular
MH  - DNA, Complementary/chemistry
MH  - Embryo, Mammalian
MH  - Fibroblasts/metabolism
MH  - Humans
MH  - Lung/metabolism
MH  - Mice
MH  - Models, Molecular
MH  - Molecular Sequence Data
MH  - Muscles/embryology/*metabolism
MH  - Protein Isoforms/chemistry
MH  - Reverse Transcriptase Polymerase Chain Reaction
MH  - Sequence Alignment
MH  - Spectrin/*chemistry/genetics
EDAT- 2000/01/08 00:00
MHDA- 2000/01/08 00:01
CRDT- 2000/01/08 00:00
PHST- 2000/01/08 00:00 [pubmed]
PHST- 2000/01/08 00:01 [medline]
PHST- 2000/01/08 00:00 [entrez]
AID - bi991458k [pii]
AID - 10.1021/bi991458k [doi]
PST - ppublish
SO  - Biochemistry. 1999 Nov 30;38(48):15721-30. doi: 10.1021/bi991458k.