---
pmid: '15454575'
title: Xin repeats define a novel actin-binding motif.
authors:
- Pacholsky D
- Vakeel P
- Himmel M
- Löwe T
- Stradal T
- Rottner K
- Fürst DO
- van der Ven PF
journal: J Cell Sci
year: '2004'
full_text_available: false
doi: 10.1242/jcs.01406
pubmed_publication_types:
- Journal Article
- Research Support, Non-U.S. Gov't
publication_type: PRIMARY_RESEARCH
---

# Xin repeats define a novel actin-binding motif.
**Authors:** Pacholsky D, Vakeel P, Himmel M, Löwe T, Stradal T, Rottner K, Fürst DO, van der Ven PF
**Journal:** J Cell Sci (2004)
**DOI:** [10.1242/jcs.01406](https://doi.org/10.1242/jcs.01406)

## Abstract

1. J Cell Sci. 2004 Oct 15;117(Pt 22):5257-68. doi: 10.1242/jcs.01406. Epub 2004
Sep 28.

Xin repeats define a novel actin-binding motif.

Pacholsky D(1), Vakeel P, Himmel M, Löwe T, Stradal T, Rottner K, Fürst DO, van
der Ven PF.

Author information:
(1)Department of Cell Biology, Institute for Biochemistry and Biology,
University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany.

Xin is a protein that is expressed during early developmental stages of cardiac
and skeletal muscles. Immunolocalization studies indicated a peripheral
localization in embryonic mouse heart, where Xin localizes with beta-catenin and
N-cadherin. In adult tissues, Xin is found primarily in the intercalated discs
of cardiomyocytes and the myotendinous junctions of skeletal muscle cells, both
specialized attachment sites of the myofibrillar ends to the sarcolemma. A large
part of the Xin protein consists of unique 16 amino acid repeats with unknown
function. We have investigated the characteristics of the Xin repeats by
transfection experiments and actin-binding assays and ascertained that, upon
expression in cultured cells, these repeats bind to and stabilize the
actin-based cytoskeleton. In vitro co-sedimentation assays with skeletal muscle
actin indicated that they not only directly bind actin filaments, but also have
the capability of arranging microfilaments into networks that sediment upon
low-speed centrifugation. Very similar repeats were also found in 'Xin-repeat
protein 2' (XIRP2), a novel protein that seems to be expressed mainly in
striated muscles. Human XIRP2 contains 28 Xin repeats with properties identical
to those of Xin. We conclude that the Xin repeats define a novel, repetitive
actin-binding motif present in at least two different muscle proteins. These
Xin-repeat proteins therefore constitute the first two members of a novel family
of actin-binding proteins.

DOI: 10.1242/jcs.01406
PMID: 15454575 [Indexed for MEDLINE]