BFSP1 explained

BFSP1 is a gene that encodes the protein filensin ("beaded filament structural protein 1") in humans.^{[1] [2]}

More than 99% of the vertebrate ocular lens is made up of terminally differentiated lens fiber cells. Two lens-specific intermediate filament proteins, phakinin (also known as CP49) and the protein product of this gene, filensin (or CP115), are expressed only after fiber cell differentiation has begun. Both proteins are found in a structurally unique cytoskeletal element that is referred to as the beaded filament (BF).

The two BFSP proteins are put into a "type VI" of intermediate filament (IF) classification. Unlike other IFs that form unbranched links, the two proteins form a network of filaments together with CRYAA.^{[3] [4]}

Further reading

• Brunkener M, Georgatos SD . Membrane-binding properties of filensin, a cytoskeletal protein of the lens fiber cells . Journal of Cell Science . 103 (Pt 3) . 3 . 709–718 . November 1992 . 1478967 . 10.1242/jcs.103.3.709 .
• Merdes A, Brunkener M, Horstmann H, Georgatos SD . Filensin: a new vimentin-binding, polymerization-competent, and membrane-associated protein of the lens fiber cell . The Journal of Cell Biology . 115 . 2 . 397–410 . October 1991 . 1918147 . 2289143 . 10.1083/jcb.115.2.397 .
• Merdes A, Gounari F, Georgatos SD . The 47-kD lens-specific protein phakinin is a tailless intermediate filament protein and an assembly partner of filensin . The Journal of Cell Biology . 123 . 6 Pt 1 . 1507–1516 . December 1993 . 7504675 . 2290875 . 10.1083/jcb.123.6.1507 .
• Sandilands A, Prescott AR, Carter JM, Hutcheson AM, Quinlan RA, Richards J, FitzGerald PG . Vimentin and CP49/filensin form distinct networks in the lens which are independently modulated during lens fibre cell differentiation . Journal of Cell Science . 108 (Pt 4) . 4 . 1397–1406 . April 1995 . 7615661 . 10.1242/jcs.108.4.1397 .
• Hess JF, Casselman JT, FitzGerald PG . cDNA analysis of the 49 kDa lens fiber cell cytoskeletal protein: a new, lens-specific member of the intermediate filament family? . Current Eye Research . 12 . 1 . 77–88 . January 1993 . 7679620 . 10.3109/02713689308999499 .
• Hess JF, Casselman JT, FitzGerald PG . Chromosomal locations of the genes for the beaded filament proteins CP 115 and CP 47 . Current Eye Research . 14 . 1 . 11–18 . January 1995 . 7720401 . 10.3109/02713689508999909 .
• Carter JM, Hutcheson AM, Quinlan RA . In vitro studies on the assembly properties of the lens proteins CP49, CP115: coassembly with alpha-crystallin but not with vimentin . Experimental Eye Research . 60 . 2 . 181–192 . February 1995 . 7781747 . 10.1016/S0014-4835(95)80009-3 .
• Hess JF, Casselman JT, Kong AP, FitzGerald PG . Primary sequence, secondary structure, gene structure, and assembly properties suggests that the lens-specific cytoskeletal protein filensin represents a novel class of intermediate filament protein . Experimental Eye Research . 66 . 5 . 625–644 . May 1998 . 9628810 . 10.1006/exer.1998.0478 .
• Yamada K, Tomita H, Yoshiura K, Kondo S, Wakui K, Fukushima Y, Ikegawa S, Nakamura Y, Amemiya T, Niikawa N . 6 . An autosomal dominant posterior polar cataract locus maps to human chromosome 20p12-q12 . European Journal of Human Genetics . 8 . 7 . 535–539 . July 2000 . 10909854 . 10.1038/sj.ejhg.5200485 . free .
• Ramachandran RD, Perumalsamy V, Hejtmancik JF . Autosomal recessive juvenile onset cataract associated with mutation in BFSP1 . Human Genetics . 121 . 3–4 . 475–482 . May 2007 . 17225135 . 10.1007/s00439-006-0319-6 . 37438074 .

Notes and References

1. Rendtorff ND, Hansen C, Silahtaroglu A, Henriksen KF, Tommerup N . Isolation of the human beaded-filament structural protein 1 gene (BFSP1) and assignment to chromosome 20p11.23-p12.1 . Genomics . 53 . 1 . 114–116 . October 1998 . 9787085 . 10.1006/geno.1998.5478 .
2. Web site: Entrez Gene: BFSP1 beaded filament structural protein 1, filensin.
3. Chaves JM, Gupta R, Srivastava K, Srivastava O . Human alpha A-crystallin missing N-terminal domain poorly complexes with filensin and phakinin . Biochemical and Biophysical Research Communications . 494 . 1–2 . 402–408 . December 2017 . 28935373 . 10.1016/j.bbrc.2017.09.088 .
4. Web site: Szeverenyi I, Cassidy AJ, Chung CW, Lee BT, Common JE, Ogg SC, Chen H, Sim SY, Goh WL, Ng KW, Simpson JA, Chee LL, Eng GH, Li B, Lunny DP, Chuon D, Venkatesh A, Khoo KH, McLean WH, Lim YP, Lane EB . Human Intermediate Filament Database . .