This is an integral membrane protein family. Family members include TMEM33/Pom33 proteins. Budding yeast Pom33 is a transmembrane nucleoporin that contributes to proper distribution and/or efficient assembly of nuclear pores [1]. Proteins in this entry also include Tts1 from fission yeasts [2], Kr-h2 (krueppel homologue 2) from flies [3] and TMEM33 from vertebrates [4]. Tts1 is required for the correct positioning of the cellular division plane by delimiting the actomyosin ring assembly at the cell equator [2]. Kr-h2 is a member of the dosage-dependent hierarchy effective upon white gene expression [3]. TMEM33 regulates the tubular structure of endoplasmic reticulum by suppressing the membrane-shaping activity of reticulons [4].

1: Pom33, a novel transmembrane nucleoporin required for proper nuclear pore complex distribution. Chadrin A, Hess B, San Roman M, Gatti X, Lombard B, Loew D, Barral Y, Palancade B, Doye V; J Cell Biol. 2010;189:795-811. PMID:20498018

2: The cortical ER network limits the permissive zone for actomyosin ring assembly. Zhang D, Vjestica A, Oliferenko S; Curr Biol. 2010;20:1029-1034. PMID:20434336

3: Kruppel homolog (Kr h) is a dosage-dependent modifier of gene expression in Drosophila. Benevolenskaya EV, Frolov MV, Birchler JA; Genet Res. 2000;75:137-142. PMID:10816971

4: Identification and characterization of TMEM33 as a reticulon-binding protein. Urade T, Yamamoto Y, Zhang X, Ku Y, Sakisaka T; Kobe J Med Sci. 2014;60:E57-E65. PMID:25612671