# CHARACTERIZATION OF SPERM MEMBRANES

> **NIH NIH R01** · PENNSYLVANIA STATE UNIVERSITY, THE · 1994 · $146,029

## Abstract

DESCRIPTION (Adapted from the applicant's abstract):  The long term
objective is to characterize structure-function relationships of ram sperm
surface membrane domains essential to fertilization.  The investigator has
shown that changes in lipid composition and properties of membrane domains
occur during epididymal maturation and that:  (a) unique cholesterol
transfer protein(s) (CTP) and lipoprotein particles (LPP) exist in male
tract fluids; (b) lipid modifications alter sperm function (induction of
the acrosome reaction (AR) and motility); and (c) membranes from two
domains (the plasma membrane (PM) overlying the acrosome and the PM
overlying the tail) can be isolated.Two questions are addressed. "How are
unique PM domains developed and maintained?"and "How do layers of membranes
(e.g., "onion-like" arrangements of PM and inner membranes) interact during
development?"  A hypothesis links progressive modifications of ram sperm PM
lipids by luminal/internal lipid transfer proteins and luminal LPP to
acquisition of membrane function. Experimental goals and questions are:
Goal 1 (determination of lipid asymmetry of PM overlying the acrosome)
answers the question:  Is PM topography distinct in mature vs immature
sperm?Two experiments characterize phospholipid flipase activities and
lipid asymmetry of isolated membrane vesicles.  Goal 2 (consequences of
lipid asymmetry of the PM overlying the acrosome) answers the question:
Does transbilayer movement of cholesterol (chol) permit fusion between two
surfaces (IPM and outer acrosomal membrane) uniquely enriched in
unsaturated phospholipid? Three experiments assess the extent of lipid
asymmetry in the PM of immature sperm, test a model system to determine the
block to the AR in immature sperm, and examine the role of transbilayer
chol movement in membrane destabilization.  Goal 3 (determination of lipid
composition/asymmetry of PM overlying the tail) answers the question:  Has
the lipid composition and asymmetry of the PM overlying the tail been
altered during epididymal transit?  Two experiments determine the lipid
composition of the tail membrane domain and assess lipid asymmetry of these
membrane vesicles.  Goal 4 (determination of the mechanism by which lipids
are altered in the PM) answers the question:  Given that the sperm cell
exists in a sea of LPPs and CTPs, how are individual surface domains
selectively modified during epididymal transit?  Four experiments test for
membrane domain specific binding of CTP)(s), determine if CTP can transfer
chol into specific membrane domains, localize a PC transfer protein in the
acrosomal region, and test for a PE transfer protein in epididymal fluids.

## Key facts

- **NIH application ID:** 2196964
- **Project number:** 5R01HD013099-14
- **Recipient organization:** PENNSYLVANIA STATE UNIVERSITY, THE
- **SAM.gov UEI:** NPM2J7MSCF61
- **Principal Investigator:** ROY H HAMMERSTEDT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $146,029
- **Award type:** 5
- **Project period:** 1979-09-01 → 1996-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2196964

## Citation

> US National Institutes of Health, RePORTER application 2196964, CHARACTERIZATION OF SPERM MEMBRANES (5R01HD013099-14). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2196964. Licensed CC0.

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