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Transmembrane and coiled-coil domains 1 (TMCO1) has a highly conserved amino acid sequence among species, indicating a critical role of TMCO1 in cell physiology. The deficiency of TMCO1 in humans is associated with cerebrofaciothoracic dysplasia (CFTD), glaucoma, osteogenesis and the occurrence of cancer. TMCO1 was recently identified as an endoplasmic reticulum (ER) Ca 2+ load-activated Ca 2+ (CLAC) release channel, which prevents ER Ca 2+ overload and maintains calcium homeostasis in the ER. However, the structural basis of the molecular function of TMCO1 channel remains elusive. To determine the structure of TMCO1, we screened the expression of TMCO1 in Escherichia coli and insect cell expression systems. TMCO1 from Dictyostelium discoideum (DdTMCO1) was successfully expressed in Escherichia coli with a high yield. The pure recombinant protein was obtained by affinity chromatography and size exclusion chromatography. The solution NMR of DdTMCO1 in DPC micelles showed three α-helical transmembrane regions., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The mutant L-type calcium channel alpha(1)-subunit gene, CACNA1F, was recently identified as the gene responsible for incomplete X-linked congenital stationary night blindness. The 6070-bp mRNA transcript is predicted to encode a 1977-amino-acid pore-forming protein with cytoplasmic amino- and carboxyl-termini separated by four homologous repeat domains, each consisting of six transmembrane segments. CACNA1F has been shown to be preferentially expressed in the retina, indicative of a specific functional role in visual processing. We have established the complete sequence of the murine orthologue of CACNA1F, namely Cacna1f. The total length of the mRNA transcript of the murine gene was established to be 6080 bp with an open reading frame that translates into a 1985-amino-acid protein. Cacna1f is highly homologous to the human sequence, with 90% identity at the amino acid level and almost perfect conservation between the functional domains. Furthermore, as in the human gene, the 3' end of the Cacna1f gene maps within 5 kb of the 5' end of the mouse synaptophysin gene in a region orthologous to Xp11.23. Using in situ hybridization, Cacna1f was found to be expressed in the inner and outer nuclear layers and the ganglion cell layer of the retina., (Copyright 2000 Academic Press.)

A novel human gene, TRPC5, was cloned from the region of Xq23 that contains loci for nonsyndromic mental retardation (MRX47 and MRX35) and two genes, DCX and HPAK3, implicated in two X-linked disorders (LISX and MRX30). Within a single YAC, we have determined the order cen-HPAK3(5'-3')-DCX(3'-5')-DXS7012E-TRPC5(3'-5' )-ter. TRPC5 encodes a 974-residue novel human protein (111.5 kDa predicted mass) and displays 99% homology with mouse TRP5, (MGD-approved symbol Trrp5) a novel member of a family of receptor-activated Ca2+ channels. It contains eight transmembrane domains, including a putative pore region. A transcript larger than 9.5 kb is observed only in fetal and adult human brain, with a relatively higher level in the adult human cerebellum. We devised an efficient method, Incorporation PCR SSCP (IPS), for detection of gene alterations. Five single-nucleotide variations in the TRPC5 gene were identified in males with mental retardation. However, these were found to be polymorphic variants. Exclusive expression of the TRPC5 gene in developing and adult brain suggests a possible role during development and provides a candidate gene for instances of mental retardation and other developmental defects., (Copyright 1999 Academic Press.)