scholarly journals Analysis of two cDNA clones encoding the B lymphocyte antigen CD20 (B1, Bp35), a type III integral membrane protein.

1988 ◽  
Vol 167 (6) ◽  
pp. 1975-1980 ◽  
Author(s):  
I Stamenkovic ◽  
B Seed
Keyword(s):  
Membrane Protein ◽  
Untranslated Region ◽  
B Lymphocyte ◽  
Integral Membrane Protein ◽  
Cdna Clones ◽  
Expression Library ◽  
Coding Sequences ◽  
Cos Cells ◽  
Cd20 Antigen ◽  
Cell Expression

Two cDNA clones encoding the pan-B cell CD20 antigen were isolated from a COS cell expression library. The two clones bear identical coding sequences and differ only in the length of the 3' untranslated region. The predicted CD20 sequence is 297 residues long and contains three hydrophobic domains, one of which is long enough to span the membrane twice. COS cells transfected with either CD20 clone express an immunoreactive protein of 33 kD.

scholarly journals Identification, sequencing and expression of an integral membrane protein of the trans-Golgi network (TGN38)

1990 ◽  
Vol 270 (1) ◽  
pp. 97-102 ◽  
Author(s):  
J P Luzio ◽  
B Brake ◽  
G Banting ◽  
K E Howell ◽  
P Braghetta ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Integral Membrane Protein ◽  
Polyclonal Antiserum ◽  
Cdna Expression Library ◽  
Cdna Clones ◽  
Expression Library ◽  
Trans Golgi Network ◽  
Sequencing And Expression ◽  
Novel Strategy ◽  
Golgi Network

Organelle-specific integral membrane proteins were identified by a novel strategy which gives rise to monospecific antibodies to these proteins as well as to the cDNA clones encoding them. A cDNA expression library was screened with a polyclonal antiserum raised against Triton X-114-extracted organelle proteins and clones were then grouped using antibodies affinity-purified on individual fusion proteins. The identification, molecular cloning and sequencing are described of a type 1 membrane protein (TGN38) which is located specifically in the trans-Golgi network.

scholarly journals Identification, molecular characterization and immunolocalization of an isoform of the trans-Golgi-network (TGN)-specific integral membrane protein TGN38

1992 ◽  
Vol 283 (2) ◽  
pp. 313-316 ◽  
Author(s):  
B Reaves ◽  
A Wilde ◽  
G Banting
Keyword(s):  
Membrane Protein ◽  
Molecular Characterization ◽  
Integral Membrane Protein ◽  
Cdna Clones ◽  
Protein Coding ◽  
Trans Golgi Network ◽  
Coding Regions ◽  
Cytoplasmic Tails ◽  
Localization Signal ◽  
Golgi Network

TGN38 is an integral membrane protein previously shown to be predominantly localized to the trans-Golgi network (TGN) of cells by virtue of a signal contained within its cytoplasmic ‘tail’ [Luzio, Brake, Banting, Howell, Braghetta & Stanley (1990) Biochem. J. 270, 97-102]. We now (i) describe the isolation of cDNA clones encoding an isoform of TGN38, (ii) present the sequence of that isoform and (iii) describe the production and use of antibodies which specifically recognize the new isoform. This isoform, designated TGN41, is also predominantly localized to the TGN. The only sequence differences between the protein coding regions of cDNA clones encoding TGN38 and those encoding TGN41 occur within the region specifying the cytoplasmic tails of the two proteins. The TGN localization signal is shown to be within the sequence common to both proteins.

scholarly journals Evidence for a conserved 95-120 kDa subunit associated with and essential for activity of V-ATPases.

1992 ◽  
Vol 172 (1) ◽  
pp. 105-112 ◽  
Author(s):  
M F Manolson ◽  
D Proteau ◽  
E W Jones
Keyword(s):  
Membrane Protein ◽  
Atpase Activity ◽  
Proton Pump ◽  
Integral Membrane Protein ◽  
Proton Pumping ◽  
Cell Fractionation ◽  
Expression Library ◽  
Suppressor Factor ◽  
Reading Frame ◽  
Cell Extracts

Vacuoles purified from Saccharomyces cerevisiae bearing the vph1-1 mutation had no detectable bafilomycin-sensitive ATPase activity or ATP-dependent proton pumping. Furthermore, the vacuolar H(+)-ATPase (V-ATPase) nucleotide binding subunits were no longer associated with vacuolar membranes yet were present at wild-type levels in yeast whole-cell extracts. The VPH1 gene was cloned by screening a lambda gt11 expression library with antibodies directed against a 95 kDa vacuolar integral membrane protein and independently cloned by complementation of the vph1-1 mutation. Deletion disruption of the VPH1 gene revealed that the VPH1 gene is required for vacuolar H(+)-ATPase assembly and vacuolar acidification but is not essential for cell viability or for targeting and maturation of vacuolar proteases. VPH1 encodes a predicted polypeptide of 840 amino acid residues (95.6 kDa) with putative membrane-spanning regions. Cell fractionation and immunodetection demonstrate that Vph1p is a vacuolar integral membrane protein that co-purifies with V-ATPase activity. Vph1p has 42% identity to the 116 kDa polypeptide of the rat clathrin-coated vesicles/synaptic vesicle proton pump, 42% identity to the TJ6 mouse immune suppressor factor, 42% identity to the Caenorhabditis elegans proton pump homologue and 54% identity to the predicted polypeptide encoded by the yeast gene STV1 (Similar To VPH1, identified as an open reading frame next to the BUB2 gene.

scholarly journals Molecular cloning of CD68, a human macrophage marker related to lysosomal glycoproteins

Blood ◽  
1993 ◽  
Vol 81 (6) ◽  
pp. 1607-1613 ◽  
Author(s):  
CL Holness ◽  
DL Simmons
Keyword(s):  
Extracellular Domain ◽  
Integral Membrane Protein ◽  
Human Macrophage ◽  
Cdna Clones ◽  
Type I ◽  
Cos Cells ◽  
Transmembrane Glycoprotein ◽  
Macrophage Marker ◽  
Glycosylation Sites ◽  
Low Levels

CD68 is a 110-Kd transmembrane glycoprotein of unknown function highly expressed by human monocytes and tissue macrophages. We have isolated cDNA clones encoding CD68 from a U937 cDNA library by transient expression in COS cells and panning with the anti-CD68 monoclonal antibodies (MoAbs) Y2/131, Y1/82A, EBM11, and Ki-M6. CD68 transcripts are constitutively present in the promonocyte cell line U937 and are upregulated by phorbol myristic acid (PMA). By contrast, CD68 transcripts are absent or present at very low levels in many hematopoietic lines including KG1, CEM, and K562, but can be induced by exposure to PMA. The cDNA sequence predicts a type I integral membrane protein of 354 residues with a heavily glycosylated extracellular domain of 298 residues containing nine potential N-linked glycosylation sites and numerous potential O-linked glycosylation sites. The extracellular domain consists of two distinct regions separated by an extended proline hinge: a membrane-distal mucin-like domain containing short peptide repeats and consisting of 54% serine and threonine residues; and a membrane proximal domain that has significant sequence homology to a family of lysosomal/plasma membrane shuttling proteins known as the lamp 1 group. CD68 is a member of a growing family of hematopoietic mucin-like molecules, including leukosialin/CD43, the stem cell antigen CD34, and the lymph node high endothelial ligand for L-selectin GlyCAM-1.

scholarly journals An integral membrane protein of the pore membrane domain of the nuclear envelope contains a nucleoporin-like region

1993 ◽  
Vol 122 (3) ◽  
pp. 513-521 ◽  
Author(s):  
E Hallberg ◽  
RW Wozniak ◽  
G Blobel
Keyword(s):  
Membrane Protein ◽  
Nuclear Envelope ◽  
Molecular Mass ◽  
Primary Structure ◽  
Integral Membrane Protein ◽  
Peptide Sequence ◽  
Relative Molecular Mass ◽  
Nuclear Pore ◽  
Cdna Clones ◽  
Membrane Domain

We have identified an integral membrane protein of 145 kD (estimated by SDS-PAGE) of rat liver nuclear envelopes that binds to WGA. We obtained peptide sequence from purified p145 and cloned and sequenced several cDNA clones and one genomic clone. The relative molecular mass of p145 calculated from its complete, cDNA deduced primary structure is 120.7 kD. Antibodies raised against a synthetic peptide represented in p145 reacted monospecifically with p145. In indirect immunofluorescence these antibodies gave punctate staining of the nuclear envelope. Immunogold EM showed specific decoration of the nuclear pores. Thus p145 is an integral membrane protein located specifically in the "pore membrane" domain of the nuclear envelope. To indicate this specific location, and based on its calculated relative molecular mass, the protein is termed POM 121 (pore membrane protein of 121 kD). The 1,199-residue-long primary structure shows a hydrophobic region (residues 29-72) that is likely to form one (or two adjacent) transmembrane segment(s). The bulk of the protein (residues 73-1199) is predicted to be exposed not on the cisternal side but on the pore side of the pore membrane. It contains 36 consensus sites for various kinases. However, its most striking feature is a repetitive pentapeptide motif XFXFG that has also been shown to occur in several nucleoporins. This nucleoporin-like domain of POM 121 is proposed to function in anchoring components of the nuclear pore complex to the pore membrane.

scholarly journals Molecular cloning of CD68, a human macrophage marker related to lysosomal glycoproteins

Blood ◽  
1993 ◽  
Vol 81 (6) ◽  
pp. 1607-1613 ◽  
Author(s):  
CL Holness ◽  
DL Simmons
Keyword(s):  
Extracellular Domain ◽  
Integral Membrane Protein ◽  
Human Macrophage ◽  
Cdna Clones ◽  
Type I ◽  
Cos Cells ◽  
Transmembrane Glycoprotein ◽  
Macrophage Marker ◽  
Glycosylation Sites ◽  
Low Levels

Abstract CD68 is a 110-Kd transmembrane glycoprotein of unknown function highly expressed by human monocytes and tissue macrophages. We have isolated cDNA clones encoding CD68 from a U937 cDNA library by transient expression in COS cells and panning with the anti-CD68 monoclonal antibodies (MoAbs) Y2/131, Y1/82A, EBM11, and Ki-M6. CD68 transcripts are constitutively present in the promonocyte cell line U937 and are upregulated by phorbol myristic acid (PMA). By contrast, CD68 transcripts are absent or present at very low levels in many hematopoietic lines including KG1, CEM, and K562, but can be induced by exposure to PMA. The cDNA sequence predicts a type I integral membrane protein of 354 residues with a heavily glycosylated extracellular domain of 298 residues containing nine potential N-linked glycosylation sites and numerous potential O-linked glycosylation sites. The extracellular domain consists of two distinct regions separated by an extended proline hinge: a membrane-distal mucin-like domain containing short peptide repeats and consisting of 54% serine and threonine residues; and a membrane proximal domain that has significant sequence homology to a family of lysosomal/plasma membrane shuttling proteins known as the lamp 1 group. CD68 is a member of a growing family of hematopoietic mucin-like molecules, including leukosialin/CD43, the stem cell antigen CD34, and the lymph node high endothelial ligand for L-selectin GlyCAM-1.

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