Limits...
Synaptopodin: an actin-associated protein in telencephalic dendrites and renal podocytes.

Mundel P, Heid HW, Mundel TM, Krüger M, Reiser J, Kriz W - J. Cell Biol. (1997)

Bottom Line: In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins.The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity.From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, University of Heidelberg, Germany. peter.mundel@urz.uni-heidelberg.de

ABSTRACT
Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9. 27 (mouse). Synaptopodin contains a high amount of proline ( approximately 20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

Show MeSH
(a) Nucleotide sequence (upper lines and numbers) and  deduced amino acid sequence (one letter code, lower lines, and  numbers) of human brain synaptopodin cDNA. Taking the first  possible start codon of the open reading frame, synaptopodin  consists of 685 aa. aa sequences determined by Edman degradation of proteolytically derived internal peptides of rat brain synaptopodin are underlined. (b) Comparison of the aa sequences  between mouse (upper lines) and human (lower lines) synaptopodin. At the protein level an 84% identity between the two species  is observed. aa sequences determined from internal peptides of  rat kidney synaptopodin are underlined. The sequence data of  human synaptopodin are available from EMBL/GenBank/DDBJ  under accession number Y11072. (c) Northern blot analysis of  synaptopodin. A single 4.4-kbp mRNA is detected in human  brain cortex (1), in rat kidney cortex (2), and rat forebrain (3). No  signal is obtained in rat cerebellum (4).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2139823&req=5

Figure 3: (a) Nucleotide sequence (upper lines and numbers) and deduced amino acid sequence (one letter code, lower lines, and numbers) of human brain synaptopodin cDNA. Taking the first possible start codon of the open reading frame, synaptopodin consists of 685 aa. aa sequences determined by Edman degradation of proteolytically derived internal peptides of rat brain synaptopodin are underlined. (b) Comparison of the aa sequences between mouse (upper lines) and human (lower lines) synaptopodin. At the protein level an 84% identity between the two species is observed. aa sequences determined from internal peptides of rat kidney synaptopodin are underlined. The sequence data of human synaptopodin are available from EMBL/GenBank/DDBJ under accession number Y11072. (c) Northern blot analysis of synaptopodin. A single 4.4-kbp mRNA is detected in human brain cortex (1), in rat kidney cortex (2), and rat forebrain (3). No signal is obtained in rat cerebellum (4).

Mentions: Synaptopodin was purified from rat kidney glomeruli and forebrain. Protein bands were cut from preparative two-dimensional blots and subjected to tryptic digestion. 20 of the resulting internal peptides of the brain protein were analyzed by Edmann degradation. Data base comparison revealed that five peptides matched with two EST clones (clones sp47 and sp91) from a human brain cDNA library. A third EST clone from the same library (clone sp17) was identified by overlapping with the 5′-end of clone sp47. To prove the identity of the renal and the brain protein, six peptide fragments of the purified glomerular protein were subjected to Edmann degradation. All of these peptide fragments revealed identical aa composition as the correponding peptide fragments of the brain protein (Fig. 3).


Synaptopodin: an actin-associated protein in telencephalic dendrites and renal podocytes.

Mundel P, Heid HW, Mundel TM, Krüger M, Reiser J, Kriz W - J. Cell Biol. (1997)

(a) Nucleotide sequence (upper lines and numbers) and  deduced amino acid sequence (one letter code, lower lines, and  numbers) of human brain synaptopodin cDNA. Taking the first  possible start codon of the open reading frame, synaptopodin  consists of 685 aa. aa sequences determined by Edman degradation of proteolytically derived internal peptides of rat brain synaptopodin are underlined. (b) Comparison of the aa sequences  between mouse (upper lines) and human (lower lines) synaptopodin. At the protein level an 84% identity between the two species  is observed. aa sequences determined from internal peptides of  rat kidney synaptopodin are underlined. The sequence data of  human synaptopodin are available from EMBL/GenBank/DDBJ  under accession number Y11072. (c) Northern blot analysis of  synaptopodin. A single 4.4-kbp mRNA is detected in human  brain cortex (1), in rat kidney cortex (2), and rat forebrain (3). No  signal is obtained in rat cerebellum (4).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139823&req=5

Figure 3: (a) Nucleotide sequence (upper lines and numbers) and deduced amino acid sequence (one letter code, lower lines, and numbers) of human brain synaptopodin cDNA. Taking the first possible start codon of the open reading frame, synaptopodin consists of 685 aa. aa sequences determined by Edman degradation of proteolytically derived internal peptides of rat brain synaptopodin are underlined. (b) Comparison of the aa sequences between mouse (upper lines) and human (lower lines) synaptopodin. At the protein level an 84% identity between the two species is observed. aa sequences determined from internal peptides of rat kidney synaptopodin are underlined. The sequence data of human synaptopodin are available from EMBL/GenBank/DDBJ under accession number Y11072. (c) Northern blot analysis of synaptopodin. A single 4.4-kbp mRNA is detected in human brain cortex (1), in rat kidney cortex (2), and rat forebrain (3). No signal is obtained in rat cerebellum (4).
Mentions: Synaptopodin was purified from rat kidney glomeruli and forebrain. Protein bands were cut from preparative two-dimensional blots and subjected to tryptic digestion. 20 of the resulting internal peptides of the brain protein were analyzed by Edmann degradation. Data base comparison revealed that five peptides matched with two EST clones (clones sp47 and sp91) from a human brain cDNA library. A third EST clone from the same library (clone sp17) was identified by overlapping with the 5′-end of clone sp47. To prove the identity of the renal and the brain protein, six peptide fragments of the purified glomerular protein were subjected to Edmann degradation. All of these peptide fragments revealed identical aa composition as the correponding peptide fragments of the brain protein (Fig. 3).

Bottom Line: In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins.The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity.From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, University of Heidelberg, Germany. peter.mundel@urz.uni-heidelberg.de

ABSTRACT
Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9. 27 (mouse). Synaptopodin contains a high amount of proline ( approximately 20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

Show MeSH