# STRUCTURE AND FUNCTION OF EPITHELIAL KERATINS

> **NIH NIH R01** · NEW YORK UNIVERSITY · 1988 · $153,946

## Abstract

Keratins are a family of water-insoluble cytoskeletal proteins that form 10
nm desmosome-associated tonofilaments in almost all vertebrate epithelial
cells.  The subunit composition of keratin filaments is highly complex,
with a total of 17 human epithelial keratins identified so far.  Using
monoclonal antibodies as a tool, we have recently demonstrated that all
known human epithelial keratins can be divided into two subfamilies, A (for
"acidic") and B (for "basic"), according to their charge properties and
their immunoreactivities with AE1 and AE3 monoclonal anti-keratin
antibodies.  We have also demonstrated that, in the two subfamilies,
keratins with the same "size-ranks" always follow similar rules of
expression.  Thus, the largest keratins of the two subfamilies, i.e., the
56.5K and 65-67K keratins of the A and B subfamilies, respectively,
represent molecular markers for phenotypic keratinization, the second
largest 55K (A) and 64K (B) keratins are unique to corneal epithelium,
whereas the third largest 54'K (A) and 59K (B) keratins are characteristic
of esophageal epithelium and other internal, nonkeratinized stratified
epithelia.  Based on these and other results, we have constructed a
unifying model which can account for almost all known variations in keratin
expression as a function of cell type, stages of embryonic development and
differentiation, cellular growth environment, and diseases including
neoplasms.  To test the validity of this model and to provide a more
detailed understanding of keratin structure and function, we will (i)
determine whether keratins of the A and B subfamilies coexist in the same
filaments at both the 10 nm tonofilament and 2 nm protofilament levels;
(ii) characterize the epitopes defined by our monoclonal anti-keratin
antibodies; (iii) define the relationship among the 56.5K keratin, 65-67K
keratins, and filaggrin; (iv) isolate individual keratin species and study
the structural and functional properties of keratin filaments reconstituted
with various combinations of these purified keratins; and (v) localize
specific keratins in hyperproliferative epidermis and in esophageal
epithelium.  Results from this study should lead to a better understanding
of the functional significance of individual keratins and the mechanisms of
normal and pathological epithelial differentiation.

## Key facts

- **NIH application ID:** 3156866
- **Project number:** 5R01AR034511-05
- **Recipient organization:** NEW YORK UNIVERSITY
- **SAM.gov UEI:** NX9PXMKW5KW8
- **Principal Investigator:** Tung-Tien Sun
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $153,946
- **Award type:** 5
- **Project period:** 1984-07-01 → 1989-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3156866

## Citation

> US National Institutes of Health, RePORTER application 3156866, STRUCTURE AND FUNCTION OF EPITHELIAL KERATINS (5R01AR034511-05). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3156866. Licensed CC0.

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