Expression of human membrane skeleton protein genes for protein 4.1 and betaIISigma2-spectrin assayed by real-time RT-PCR.
The proteins, spectrin and 4.1 confer support and resilience to animal cell membranes, and promote assembly of multimeric, membrane-bound signalling complexes. Protein 4.1 also plays important roles in tumour suppression and the regulation of cell proliferation. To assess relative tissue expression of the four genes encoding human protein 4.1, we measured mRNA levels using quantitative real-time polymerase chain reaction. We compared 4.1 expression with that of a major splice variant of spectrin, betaIISigma2 that has a shortened C-terminus lacking a pleckstrin homology domain. mRNA for 4.1R is four-fold higher in bone marrow than in tissues with the next highest prevalence: cerebellum, lung, testis and thymus. 4.1G mRNA is highly expressed in brain, spinal cord and testis; 4.1N in brain, spinal cord and adrenal gland; 4.1B in testis, brain, spinal cord, and kidney. Thus, 4.1N, 4.1B and 4.1G all show high accumulation in nervous tissues. mRNA for betaIISigma2-spectrin is ubiquitous, but most abundant in cardiac and nervous tissues. Comparative transcript abundance was analysed in heart and brain. betaIISigma2-spectrin was the most abundant transcript in heart with levels 5 fold greater than 4.1G or 4.1N and at least 9 fold greater than 4.1B. In brain, 4.1N was the most abundant transcript, with levels 2.4 fold greater than 4.1B and at least 4 fold greater than 4.1G or betaIISigma2-spectrin. 4.1R abundance was very low in both tissues. Whilst we expected that 4.1 mRNAs would feature highly in muscle and nerve, we note their high abundance in testis, indicating previously unsuspected functions in reproduction.
Taylor-Harris
Pamela M
PM
Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London SE1 1UL, UK.
Felkin
Leanne E
LE
Birks
Emma J
EJ
Franklin
Rodney C G
RC
Yacoub
Magdi H
MH
Baines
Anthony J
AJ
Barton
Paul J R
PJ
Pinder
Jennifer C
JC
D001798:Blood Proteins / Q000096:biosynthesis / Q000235:genetics*; D001853:Bone Marrow / Q000378:metabolism; D002490:Central Nervous System / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics*; D009206:Myocardium / Q000378:metabolism; D009479:Neuropeptides / Q000096:biosynthesis / Q000235:genetics; D009928:Organ Specificity; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013049:Spectrin / Q000096:biosynthesis / Q000235:genetics*; D013737:Testis / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000235:genetics
D001798:Blood Proteins; D003598:Cytoskeletal Proteins; C116887:EPB41L3 protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D012333:RNA, Messenger; C452439:SPTBN1 protein, human; D025521:Tumor Suppressor Proteins; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D013049:Spectrin