title: Comprehensive characterization of protein 4.1 expression in epithelium of large intestine.
abstract: The protein 4.1 family consists of four members, 4.1R, 4.1N, 4.1B and 4.1G, each encoded by a distinct gene. All 4.1 mRNAs undergo extensive alternative splicing. Functionally, they usually serve as adapters that link actin-based cytoskeleton to plasma membrane proteins. It has been reported that 4.1 proteins are expressed in most animal cell types and tissues including epithelial cells and epithelial tissues. However, the expression of 4.1 proteins in large intestine has not been well characterized. In the present study, we performed RT-PCR, western blot and immunohistochemistry analysis to characterize the transcripts, the protein expression and cellular localization of 4.1 proteins in the epithelia of mouse large intestine. We show that multiple transcripts derive from each gene, including eight 4.1R isoforms, four 4.1N isoforms, four 4.1B isoforms and six 4.1G isoforms. However, at the protein level, only one or two major bands were detected, implying that not all transcripts are translated and/or the proteins do not accumulate at detectable levels. Immunohistochemistry revealed that 4.1R, 4.1N and 4.1B are all expressed at the lateral membrane as well as cytoplasm of epithelial cells, suggesting a potentially redundant role of these proteins. Our findings not only provide new insights into the structure of protein 4.1 genes but also lay the foundation for future functional studies.
authors.affiliation: Department of Biophysics, Peking University Health Science Center, Xueyuan Road, Haidian District, Beijing, 100191, China.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Zhang
authors.forename: Shaomin
authors.initials: S
authors.lastname: Yang
authors.forename: Chao
authors.initials: C
authors.lastname: An
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Hongxia
authors.initials: H
authors.lastname: Yan
authors.forename: Yumin
authors.initials: Y
authors.lastname: Huang
authors.forename: Jinlei
authors.initials: J
authors.lastname: Song
authors.forename: Changcheng
authors.initials: C
authors.lastname: Yin
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Baines
authors.forename: Narla
authors.initials: N
authors.lastname: Mohandas
authors.forename: Xiuli
authors.initials: X
authors.lastname: An
mesh_terms: D000818:Animals; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism*; D007420:Intestine, Large / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
chemical_list: D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; C028841:erythrocyte membrane band 4.1 protein